• Hydropower is mainly located at hilly area.
• Hydroelectric power plant is economical, renewable and conventional.
• The amount of electrical energy that can be generated by a hydroelectric power plant depends upon quantity of water.
• Hydropower cannot produce continuous power supply.
• Potential of Nepal:

Gross Potential: 83 GW

Technical Potential: 44 GW

Economical Potential: 42 GW

• Highest hydropower potential of Nepal is Karnali and Mahakali river basin i.e (32000 MW + 4000 MW = 36000 MW)
• Hydropower currently supplies around 17% of the worlds total electric power supply.
• Potential of world:

Gross Potential: 38,607 TWhr/yr

Technical Potential: 14,605 TWhr/yr

Economical Potential: 8,772 TWhr/yr

• Installed capacity in world:

World: 1416 GW

China: 421 GW

Brazil: 110 GW

USA: 102 GW

Canada: 83 GW

Nepal: 3 GW

• Nepal first hydropower plant was Pharping hydropower plant in 1911 AD capacity (500 KW).
• First hydropower of Nepal from private sector is Khimti in 2000 AD by HPL capacity (60 MW).
• License for hydropower projects are:

Survey: 5 yrs (Period)

Generation: 30 yrs (Export)

                       35 yrs (Domestic) …..+ 5 yrs (incase of Hydrological condition)

Transmission: 15 yrs (add 10 yrs)

• Types of hydropower in Nepal:

PROR:

a.Upper Tamakoshi (456 MW)

b. Kaligandaki (144 MW)

c.Marshadi (69 MW)

d.Middle Marshandi (70 MW)

Storage:

a. Kulekhani (60 MW)

• World hydropower plants:

1.Three George Dam Hydropower (22.5 GW)

2.Baihetan Dam (16 GW)

3. Itaipu Dam Hydropower (14 GW)

References:

• Dandekar, M. M., & Sharma, K. N. (2010). Water Power Engineering. Vikas Publishing House.
• Punmia, B. C., Pande, B. B. L., Jain, A. K., & Jain, A. K. (2016). Irrigation and Water Power Engineering. Laxmi Publications.
• Singh, Bharat (2018). Fundamentals of Hydrology and Hydropower Engineering. Nem Chand & Bros.
• Central Water Commission, Government of India (2019). Handbook on Hydroelectric Engineering.
• International Energy Agency (IEA) (2021). Hydropower Status Report. Retrieved from www.iea.org
• Nepal Electricity Authority (NEA) (2022). Annual Report on Hydropower Projects in Nepal. Retrieved from www.nea.org.np
• United States Bure

The post Hydropower Project Planning: Capsule Summary appeared first on OnlineEngineeringNotes.

Power house:

• Structural complex where all the equipment for producing and providing electricity are suitably arranged.

Classification of powerhouse:

a. Surface powerhouse:

• Located on the surface of the land so that it has less space restriction.
• Foundation analysis of such structure should be examined carefully.
• If solid bed is not available in surface powerhouse special treatment should be done.

b. Underground powerhouse:

• If there is restriction or not enough space then this powerhouse is constructed.
• Economical.

General arrangement of powerhouse:

1.Superstructure:

• The structure from generator floor to roof of power house.
• Consist of generator, control room, auxiliary equipment needed for ventilation and cooling.

2.Intermediate structure:

• The structure from turbine axis to top of generator.
• Consist of casing, generator and its appurtenances.
• Access to turbine runner.

3.Sub structure:

• Structure that is situated below the axis of turbine.
• Consist of draft tube, tail water channel and galleries.

1.2 General dimension calculation of powerhouse

1.Machine hall (Unit bay)

a. Length:

• The length of machine hall depends upon the number of units, the distance between the units, size of machine and the clearance.
• The standard distance of scroll casing is about 4.5D to 5D.

Where, D= Diameter of turbine

• Minimum clearance is about 2 to 3m.

b. Width:

• Width of machine hall is also determined by the size and clearance space from the walls.
• Width of machine hall can be (5D+2.5)m.
• Width is kept as less as possible.

c. Height:

• Height of machine hall is fixed up by head room requirement of crane operation.
• Generally, 2 to 2.5 m head requirement is for crane operation.

2. Loading Bay:

• It is a space where the heavy vehicle can be loaded and unloaded.
• Dismantled parts of machine can be placed and assembling of equipment is done.
• Load bay floor will have width at least equal to the center distance of machine.

3. Control Bay:

• Main room where equipment like runner, gate valve, generator etc are controlled.
• It may be adjacent to the machine hall as it sends instruction to operation bay.

References:

• Dandekar, M. M., & Sharma, K. N. (2010). Water Power Engineering. Vikas Publishing House.
• Punmia, B. C., Pande, B. B. L., Jain, A. K., & Jain, A. K. (2016). Irrigation and Water Power Engineering. Laxmi Publications.
• Singh, Bharat (2018). Fundamentals of Hydrology and Hydropower Engineering. Nem Chand & Bros.
• Central Water Commission, Government of India (2019). Handbook on Hydroelectric Engineering.
• International Energy Agency (IEA) (2021). Hydropower Status Report. Retrieved from www.iea.org
• Nepal Electricity Authority (NEA) (2022). Annual Report on Hydropower Projects in Nepal. Retrieved from www.nea.org.np
• United States Bureau of Reclamation (2020). Design of Small Dams. U.S. Government Printing Office.

The post Powerhouse Planning appeared first on OnlineEngineeringNotes.

Hydro mechanical equipment:

• Those equipment that convert either hydraulic energy into mechanical energy or mechanical energy into hydraulic energy.

Turbine:

• Turbine are the hydro-mechanical equipment that convert hydraulic energy into mechanical energy.

Classification of hydraulic turbine

A. Based on nature of energy head possessed by water at inlet

1. Impulse or velocity turbine

• A turbine in which water entering runner possess kinetic energy only.
• Pressure is atmospheric at inlet and outlet of the turbine.
• Example: Pelton turbine.

2. Reaction turbine

• The turbine in which water entering the runner possess pressure as well as kinetic energy.
• Enclosed by tight casing.
• Example: Kaplan turbine, Francis turbine etc.

B. Based on direction of flow

1. Tangential flow turbine

• The flow in turbine is in tangential direction of rotation of runner.
• Example: Pelton turbine.

2. Radial flow turbine

• Water moves toward the axis of rotation of runner or away from it.

3. Axial flow turbine

• Water flows parallel to the axis of rotation.
• Example: Kaplan turbine

4. Mixed flow turbine

• Water enters radially inward at inlet and discharges water at outlet in direction parallel to axis of rotation of runner.
• Example: Francis turbine

C. Based on head

1. Low head turbine (15m-60m)

• Example: Kaplan turbine

2. Medium head turbine (60m -250m)

• Example: Francis turbine

3. High speed turbine (>250m)

• Example: Kaplan turbine

D. Based on specific speed

1. Low specific speed turbine (8-30)

• Example: Pelton turbine

2. Medium specific speed turbine (50-250)

• Example: Francis turbine

3. High specific speed turbine (250-850)

• Example: Kaplan turbine

Selection of turbine:

1.Available head and its fluctuation

• Very high head (H>350m): Pelton turbine
• High head (150-350m): Pelton or Francis
• Medium head (60-150m): Francis turbine
• Low head (<60): Kaplan and Francis turbine

2. Efficiency

• Turbine that gives highest overall efficiency for various operating condition should be selected.

3. Specific speed

• High specific speed is required where head is low and output is large.

4.Rotational speed

• Depends upon specific speed but in practice it should have higher value.

5. Water quality

• Quality of water is more important for impulse turbine than reaction turbine.

6. Conveyance or maintenance

• Impulse turbine has less cost of maintenance that reaction turbine.

7. Deposition of turbine shaft

• Vertical shaft arrangement is better for large size turbine.
• Horizontal shaft arrangement is preferred for large size impulse turbine.

Scroll case, draft tube and tail race canal:

Draft tube:

• It is a pipe of gradually increasing area which connects the outlet of runner to the tail race.
• Used for discharging water from the exit of the turbine to the tail race.

Function of draft tube:

• Helps to recover the velocity head of the water out the runner.
• Helps to reduce turbulence and minimize cavitation.
• Increase efficiency of turbine.
• Reduce velocity of water exiting the turbine.
• Reduce noise and vibration from turbine.

Types of draft tube:

• Conical draft tube
• Simple elbow tube
• Moody spreading tube
• Draft tube with circular inlet and rectangular outlet

1.2 Electro-mechanical installation

Introduction to generator and their types:

Generator:

• Device that converts mechanical energy into electrical energy.

Types of generator:

1.Synchronous generator

• Used to maintain a constant frequency in the electricity grid.
• More expensive than asynchronous generator.

2.Asynchronous generator

• Used to provide additional power during peak demand.
• Cannot generator AC power when disconnected from grid.

1.3 Pumps

Centrifugal pumps:

• A centrifugal pump is a mechanical device used to more water by converting rotational energy into kinetic energy.
• Used in hydropower to transfer water from a low pressure area to a higher pressure area.

Reciprocating pump:

• A pump uses piston to move water.
• Create pressure to move water through pipeline.

References:

• Dandekar, M. M., & Sharma, K. N. (2010). Water Power Engineering. Vikas Publishing House.
• Punmia, B. C., Pande, B. B. L., Jain, A. K., & Jain, A. K. (2016). Irrigation and Water Power Engineering. Laxmi Publications.
• Singh, Bharat (2018). Fundamentals of Hydrology and Hydropower Engineering. Nem Chand & Bros.
• Central Water Commission, Government of India (2019). Handbook on Hydroelectric Engineering.
• International Energy Agency (IEA) (2021). Hydropower Status Report. Retrieved from www.iea.org
• Nepal Electricity Authority (NEA) (2022). Annual Report on Hydropower Projects in Nepal. Retrieved from www.nea.org.np
• United States Bureau of Reclamation (2020). Design of Small Dams. U.S. Government Printing Office.

The post Hydro mechanical and Electromechanical Equipment appeared first on OnlineEngineeringNotes.

• Spillway is a structure used to control and manage the flow of water in hydropower plant.

Function of spillway:

• Helps to maintain water level of the reservoir at a constant level.
• Helps to regulate the flow of water.
• Prevent from flooding by allowing controlled released of water.
• Protect hydropower from overtopping.
• Helps to reduce erosion downstream.

Types of spillway:

A. Based on control mechanism

a. Controlled spillway:

• It has mechanical structure or gate to regulate the rate of flow.

b. Uncontrolled spillway:

• Does not have gate.

B. Based on purpose

a. Main spillway:

• Designed for safe passage of designed maximum flood.

b. Auxiliary spillway:

• Used in extreme cases to prevent a catastrophic breach to the dam.

c. Emergency spillway:

• Used in emergency situation when incoming discharge exceeds maximum design flood.

C. Based on prominent feature

a. Free fall spillway:

• It is one which flow drops freely from the crest.
• Not suitable for high drops.

b. Ogee spillway:

• Ogee spillway is a modified type of vertical drop spillway which has a control weir that is ogee shaped in profile.
• It is curved structure that is designed to provide a more efficient flow of water over a dam than traditional spillway.
• Used in high solid gravity dam.

c. Side channel spillway:

• Control weir is placed alongside approximately parallel to spillway discharge channel.

d. Chute spillway:

• Transfer excess water from behind the dam.

e. Siphon spillway:

• Difference in height between intake and outlet create pressure difference to remove water.

Cavitation:

• Formation of bubbles in fluid due to decrease in pressure.
• Occurs when the flow of water through the turbine is too fast, creating vacuum.
• Reduce efficiency of turbine.

Prevention measure:

• Install anti-cavitation device such as aerator.
• Reduce water velocity by increasing the size of spillway.

1.2 Method of energy dissipation

Energy dissipation:

• Minimizing the flow velocity to acceptable limit.

Type of energy dissipation:

1.Ski-jump:

• Suitable when foundation rock is good quality to withstand erosion.
• When tail water is low depth ski-jump formation takes place.

2. Flip bucket (Roller Bucket):

• Used to dissipate energy in situation where tail water depth is insufficient for the formation of hydraulic jump.

3. Stilling basin:

• Used to dissipate the energy of discharge passing the overflow section before the discharge is returned to the downstream river channel.

Types:

a. Horizontal apron stilling basin

b. Sloping apron stilling basin

References:

• Dandekar, M. M., & Sharma, K. N. (2010). Water Power Engineering. Vikas Publishing House.
• Punmia, B. C., Pande, B. B. L., Jain, A. K., & Jain, A. K. (2016). Irrigation and Water Power Engineering. Laxmi Publications.
• Singh, Bharat (2018). Fundamentals of Hydrology and Hydropower Engineering. Nem Chand & Bros.
• Central Water Commission, Government of India (2019). Handbook on Hydroelectric Engineering.
• International Energy Agency (IEA) (2021). Hydropower Status Report. Retrieved from www.iea.org
• Nepal Electricity Authority (NEA) (2022). Annual Report on Hydropower Projects in Nepal. Retrieved from www.nea.org.np
• United States Bureau of Reclamation (2020). Design of Small Dams. U.S. Government Printing Office.

The post Spillways and Energy Dissipaters appeared first on OnlineEngineeringNotes.

Power Canal:

• A power canal refers to a canal used for hydraulic power generation, rather than for transport.
• Flow is open channel.

Suitability of canal in hydropower system

• Canal can be a good medium of conveyance where construction of tunnel is expensive.
• Construction of canal is easier than tunnel.
• Hydropower can be merged with other purposes if the conveyance system is canal.

1.2 Hydraulic tunnels

Tunnel:

• Tunnel is an underground passage made without removing the overburden.
• They are constructed fort the conveyance of flow or the transportation or for storage purpose.

Types of tunnel:

a.Pressure tunnel:

• The tunnel which flow take place with pressure is called pressure tunnel.

b.Non-pressure tunnel:

• The tunnel is which open channel flow takes place is called non-pressure tunnel.

Purpose of tunnel:

• To connect two sources of water as reservoir.
• To discharge excess flood water.
• To divert river water during construction of dam.

Advantage of tunnel:

• Reduce land acquisition, resettlement issue, forest clearance etc.
• Less environmental effect.
• Low maintenance cost.
• Optimum space consumption.
• Time saving i.e shortest route to connect two points.

Disadvantage of tunnel:

• High construction cost.
• Construction period is long.
• High construction risk.
• Expensive investigation.
• Additional cost for lighting and ventilation.

Shape and size of tunnel:

Size of tunnel:

• Minimum diameter should not be greater than 2m for circular section.
• Width and height should be greater than 1.9 m and 2.1 m respectively for other shape.

Shape of tunnel:

a.Circular section:

• Most suitable for structural consideration.
• Difficult for excavation.

b.D-shape section:

• Suitable for tunnel located in good quality rock.
• Advantage of D-shaped is its added width of invert which gives more working space.

c.Horse-shoe shape:

• These section are compromise between circular and D-shaped section.
• Strong to withstand external rock and water pressure.

d.Egg shaped section:

• When tunnel is stratified, soft and very closely laminated and high pressure then egg shaped is used.

Stress in tunnel:

• Lateral active earth pressure.
• Reaction pressure due to elastic deformation.
• Over burden pressure.
• Hydrostatic pressure.
• Earthquake pressure.

Hardness coefficient of rock:

Hydraulic design of tunnel:

a.Non-pressurized tunnel:

• Design of non-pressurized tunnel is similar to design of canal.

b.Pressurized tunnel:

• The design of pressure flow tunnel is computed as pipe flow and head loss is computed using Darcy’s frictional factor.

Tunneling method:

1. Cut and cover method:

• Cut and cover method is a tunneling technique used for constructing tunnel for water supply, irrigation and hydropower projects.
• It involves excavating a trench, laying a tunnel lining and then backfilling the trench.
• Used for shallow tunnel.

2.Drill and blast method:

• This method of tunneling is hydropower which involves using explosives to break through rock and excavate a tunnel.
• Also, it involves drilling holes into the rock, placing explosive into the holes and detonating the explosive to break the material apart.
• Process is repeated until tunneling is completed.

3.Tunnel boring method:

• It involves using a machine to excavate a tunnel through and soil.
• Used to create large and long tunnel which would otherwise be too difficult and time consuming to complete manually.
• It is capable of cutting hard rock and soil while simultaneously supporting tunnel wall.

4.Shaft method:

• A technique of digging a vertical or inclined shaft from the surface to the underground tunnel.

5.Heading and benching method:

• In this method it involves the excavation of two parallel tunnels with an intermediate bench.

Support of tunnel:

1. Steel ribs:

• They are made from I-beam or H-beam bent for requirement particular tunnel cross section.

2.Rock bolt:

• This is flexible method and used to prevent tunnel collapse and provide stability to tunnel.

3.Timber support:

• Timber is used in variety of ways to provide temporarily support.

4. Wire mesh:

• Heavy steel wire mesh and steel mats are used.

5. Grouting:

• Process of injecting cement or grout into the surface around tunnel to provide water tight seal.

Lining of tunnel:

• After excavation of tunnel, lining is done to increase hydraulic capacity of the tunnel to reduce resistance, to increase strength and to reduce losses from tunnel.

Advantage:

• Increase the stability and strength of tunnel.
• Reduce the risk of ground water infiltration into tunnel.
• Reduce risk of collapse.
• Reduce maintenance cost.
• Increase durability of tunnel.

Types of lining:

• Shotcrete lining
• Plain concrete lining
• Steel lining
• Reinforced concrete lining

1.3 Forebay and Surge tank

Forebay:

• It is the structure located at the beginning of the penstock shaft that supplies the required flow to the turbine during start up, accommodate the rejected flow and reduce water hammer effect.

Function of forebay:

• To allow for the transition from open channel flow to pressure flow condition.
• To serve as secondary settling basin.
• To regulate the flow into the penstock.
• To release surge pressure as the wave travels out of the penstock pipe.

Components of forebay:

• Spillway
• Trash rack
• Flushing sluice
• Penstock pipe
• Valve or gate chamber

Surge tank:

• It is the open topped storage structure which is connected to the penstock at a suitable location.
• Always located close to power house to reduce length of penstock.

Function of surge tank:

• To reduce water hammer.
• To use or receive or store water when the load on the turbine is suddenly decreased.
• Provide protection to penstock.
• Temporarily supply water when load on the turbine is suddenly increased.

Types of surge tank:

a.Simple surge tank:

• This surge tank is of uniform cross section and acts as a reservoir.
• Directly connected to penstock and unrestricted opening.
• Large in size.

b.Restricted orifice type:

• This surge tank has restricted orifice between pipeline and the tank which allows more rapid pressure changes in pipeline than simple surge tank.

c.Different surge tank:

• In this surge tank the head building function is achieved through the riser shaft and the storage function is achieved through outer shaft.

Design of mass oscillation in surge tank:

1.4 Penstock and Pressure shaft

Penstock:

• It is a pipe that conveys the flow from forebay or surge tank to the turbine.

Water hammer:

• It is a pressure surge caused by sudden stop or start of flow of water in pipe.

Cause:

• Power failure.
• Mechanical failure of control device.

Economic diameter of penstock pipe:

• With the increase of diameter of penstock the head loss decrease as given by Darcy’s formula and hence the revenue loss decreases. At the same time, with the increase in the diameter of the penstock the cost of the pipe increases. Thus, the diameter of the penstock pipe that optimize these two costs is called economic diameter of penstock.

Determination of economic diameter of penstock:

References:

• Dandekar, M. M., & Sharma, K. N. (2010). Water Power Engineering. Vikas Publishing House.
• Punmia, B. C., Pande, B. B. L., Jain, A. K., & Jain, A. K. (2016). Irrigation and Water Power Engineering. Laxmi Publications.
• Singh, Bharat (2018). Fundamentals of Hydrology and Hydropower Engineering. Nem Chand & Bros.
• Central Water Commission, Government of India (2019). Handbook on Hydroelectric Engineering.
• International Energy Agency (IEA) (2021). Hydropower Status Report. Retrieved from www.iea.org
• Nepal Electricity Authority (NEA) (2022). Annual Report on Hydropower Projects in Nepal. Retrieved from www.nea.org.np
• United States Bureau of Reclamation (2020). Design of Small Dams. U.S. Government Printing Office.

The post Water Conveyance Structure appeared first on OnlineEngineeringNotes.

1.Diversion weir:

• Structure built in a river to divert water from the main channel into a canal or penstock.

2.Intake:

• Opening to draw design flow from the river.

3.Gravel trap:

• Used to reduce the velocity  of water and prevent erosion.

4.Settling basin:

• Used to capture sediment and other debris.

5.Headrace canal:

• Used to transport water from source to power plant.

6.Penstock:

• Pipe or conduit used to convey water from reservoir to turbine.

7.Power house:

• Building with equipment used to generate electricity from hydropower.

8.Tailrace:

• Outlet channel where used water is released.

1.2 Different type of intake

Intake

Function:

• Control flow of water.
• Prevent entry of debris, trash and ice etc.
• Minimize sediment entry.

Location of intake:

• Should be located at upstream side of power house.
• Located in an area with large and consistent river flow.
• Should be located such it has minimum environmental impact.
• Should be located in area free from debris and sediment.

Types of intake:

1. Runoff river intake:

a.Side intake:

• Common type of intake in ROR plant.
• Suitable for mild slope river.
• Longitudinal axis of the intake is aligned perpendicular to the axis of the river.

b.Frontal intake:

• Suitable for clean and wide river.
• Longitudinal axis of the intake is aligned parallel to the axis of river.
• Trash and debris are attracted towards intake.

c.Drop intake or Bottom rock intake:

• Trash rack is provide over the intake.
• Suitable for very steep river carrying boulder.
• Simple and inexpensive.

2.Reservoir intake:

a.Dam intake:

• It is provided in the body of the dam and used in high head hydroelectric plant.

b.Tower intake:

• Used in large projects.
• Tower intake are categorized as dry tower intake and wet tower intake.

c.Submerged intake:

• Used in small power plants.
• Used in reservoir or river which do not have higher sediment concentration.
• Economical.

d. Shaft intake:

• Vertical shaft driven into the river bed which carries water through underground conveyance system to the power house for power generation.

Importance of intake:

• Helps to ensure a steady flow of water to the turbine. Hence, increasing their efficiency.
• Help to reduce entry of debris in turbine and preventing from damage.
• Used to divert water from one area to another in order to meet demand or balance out river flow.
• Necessary for proper functioning hydropower system.
• Controls water level.

Consideration for location of intake:

• Adequate inflow.
• Least debris intake.
• Least environmental impact.

Design concept in intake:

• Design suitable type of intake based on site and hydraulic condition.
• Satisfy the velocity condition.
  • Approach velocity= 1m/s
  • Trash rack= 0.6-0.75 m/s
  • Intake gate= 1-2 m/s
• Decide number of opening of intake.
• Account for contraction effect due to abutment or piers.
• Calculate hydraulic losses i.e transition loss, exit loss etc.
• Ensure no entry of air.

i.e The system can trap air due to the formation of vertex due to hydraulic jump condition.

• Ensure the release of trapped air to avoid formation of vacuum.

Head loss in trash rack:

a.Kirschmer’s formula

b. General formula

1.3 Performance standards of headwork’s

Control of bed load and floating debris intake

1.Trash rack:

• Placed at the entrance to the intake to prevent entry of floating debris and large stone.
• Trash rack are fabricated with stainless steel or plastic bars.

2.Undersluice:

• Provided to flush out the sediments deposited in front of the intake and control the bed level in its approach area.
• Located close to intake.

3.Gravel trap:

• Constructed close to intake in order to prevent gravel from getting into the canal.
• Main function is to collect the bed load.
• Location is based on the site condition, availability of flushing head and gravel carrying capacity of the canal.

Hydraulic design of gravel trap:

Hydraulic design of gravel trap is similar to settling basin design.

Himalayan intake:

• Himalayan intake is a special type of intake that has proper system for management of both floating debris and bed load.
• It is a geometric design of an intake structure to be used in run-off-river hydropower intake in steep Himalayan river.
• The purpose is to maintain a reservoir volume for daily peaking by providing means of flushing of sediments from reservoir.
• The intake is designed to function in a river which carry both floating debris and large amount of coarse sediments.

1.4 Sediment handling measures

Himalayan river are more prone to erosion due to :

• Young geology
• Fragile geology
• Intense rainfall
• Steep catchment

Sediment handling measure:

1.Catchment management:

• Vegetation screen may be developed by promoting the growth of vegetation in the catchment as well as the entrance to the headwork.
• It would trap a large amount of sediment if flood water pass through them before entering the head works hence helping in reducing the sediment and prevent from entering.

2.Control sediment deposition

• Water having higher sediment content is discharged to the downstream through the undersluice.

3.Construction of sediment excluder or sediment ejector:

• Sediment excluder are constructed in the river pocket.
• Sediment ejector are constructed in the canal.

4.Construction of sloping intake

5.Construction of gravel trap

6.Construction of sedimentation tank

Settling basin:

• It is the structure to remove suspended sediments from the conveyance water for power plant.
• The main principle of the design of settling basin is to reduce the main velocity of the flow.

Purpose of settling basin:

• To remove the fine grained suspended matter from water drawn from intake.
• To remove the suspended particle and minimize the wear and tear of nozzle and runner of turbine.
• To remove sediment as it causes abrasion and erosion of civil structure’s.
• To operate and maintain power plant.

Design criteria of settling basin:

1. Optimum removal of sediment:

• Settling basin shall be designed to remove as much of sediment load in water in econological way.
• As removal of all suspended sediment is not physically possible so the design shall attempt to remove as much of possible so that hydraulic transport capacity of water conveyance sytem is maintained.

2.Settling capacity:

• The size of basin must be large enough to allow a percentage of fine sediment to fall out of suspension and deposited on the bottom.

3.Storage capacity:

• The basin should be able to store the settled particle for sometime unless it is flushed out.

4.Flushing capacity:

• The basin should be able to flush all settled particle along with the incoming flow in the basin by opening flushing gate or valves.

Components of settling basin:

Design of settling basin:

Estimation of sediment volume:

1.5 Flushing of settling basin

1.Continuous flushing type:

• These type of basin are designed with hoppers. The settled particle pass through the bottom of the hoppers to the collecting channel and are flushed continuously.
• Uses surplus water for flushing i.e about 10% of plant discharge.
• Does not interfere in power production during flushing process.
• Complex compared to discontinuous type.
• Main problem is clogging of sediment extracting system.
• Example: Hopper type and Hydro cyclone.

2.Discontinuous flushing type (Periodic or Intermittent):

• Sediment are not flushed continuously.
• Simple in design and are much less susceptible to clogging.
• In first phase, the suspended sediment are allowed to settle in the settling zone.
• In second phase the deposited sediment are removed by different systems.
• Flushing is only required when settling basin is overloaded.

References:

• Dandekar, M. M., & Sharma, K. N. (2010). Water Power Engineering. Vikas Publishing House.
• Punmia, B. C., Pande, B. B. L., Jain, A. K., & Jain, A. K. (2016). Irrigation and Water Power Engineering. Laxmi Publications.
• Singh, Bharat (2018). Fundamentals of Hydrology and Hydropower Engineering. Nem Chand & Bros.
• Central Water Commission, Government of India (2019). Handbook on Hydroelectric Engineering.
• International Energy Agency (IEA) (2021). Hydropower Status Report. Retrieved from www.iea.org
• Nepal Electricity Authority (NEA) (2022). Annual Report on Hydropower Projects in Nepal. Retrieved from www.nea.org.np
• United States Bureau of Reclamation (2020). Design of Small Dams. U.S. Government Printing Office.

The post Run-of-River layout of components in a typical power plant appeared first on OnlineEngineeringNotes.

Gross head:

• It is the total vertical distance between the inlet and outlet of the hydropower system.

Net head:

• It is the difference between the gross head and the hydraulic losses (due to friction, turbulence etc.)

Operating head:

• It is the head available to drive the turbine, which is the difference between the total head and the losses resulting from the operating condition of the turbine.

Design head:

• It is the head used to design the turbine, which must be greater than the operating head.
• It includes the operating head plus a safety margin.

1.2 Plant and installed capacity

Plant capacity:

• It is the total power generating capacity of plant with respect to available discharge head and efficiency.

Installed capacity:

• It is the economically feasible capacity of the plant.
• It is the maximum power that can be generated by all generator at normal head and full flow.

Power (P) = η⋅ρ⋅g⋅H⋅Q

Where,

P = Power (Watts)

η = Efficiency of the system (decimal form, typically 0.7–0.9)

ρ = Density of water (≈1000 kg/m³)

g = Acceleration due to gravity (9.81 m/s²)

H = Net head (meters) (height difference between intake and turbine)

Q = Flow rate (m³/s)

1.3 Energy flow diagram (related to FDC), firm and secondary power and energy

Energy flow diagram:

• Energy flow diagram in hydropower engineering represents the flow of energy generated by the hydropower system over time.
• This diagram is related to flow duration curve because the flow duration curve is used to estimate the amount of energy that can be generated over a certain period of time.
• It shows how much energy will be distributed among different components of the system.

Primary power (Firm Power):

• The net amount of power which is continuously available from a plant to consumer at any time.

Secondary power:

• The excess power available over the firm power.
• Not available at any time.

1.4 Economic consideration in HP system

• Economic consideration in hydropower system refers to the cost associated with the development, operation and maintenance of the system.

Marginal cost-benefit approach:

• It is an economic analysis that examine the cost and benefits of hydropower.
• It identifies the marginal cost of generating electricity and environmental and social impact of power generation.
• It considers long-term economic impact such as potential for increased employment, increased tax revenues, improved public service and improve quality of life.
• It helps to identify the most cost-effective ways to harness the power of hydropower.

Optimization approach:

• It is the process of finding the most economically viable solution to the problem of optimizing the use of hydropower resources.
• This involves optimizing the use of water, power and other resources to maximize the benefits to be gained from the use of hydropower while minimizing the cost and risk associated with it.
• It includes using the most efficient means of generating, consuming and storing energy and ensuring that all energy sources are used in the most sustainable manner.

1.5 Estimation of power and energy potential and its demand prediction method

• The estimation of the power and energy potential in hydropower engineering is based on the amount of water flow, the head of the water and the turbine efficiency.
• It is calculated by using equation:

Power = Energy/Time

Method of demand prediction:

a.Class wise consumption:

• Electricity is consumed at different rate by different people. Residental area will have different energy consumption than commercial area.

b.Historical trends:

• The past recorded data can be mathematically interpreted and hence future demand can be forecasted using regression analysis.

c.GDP:

• The data of GDP and per capita energy consumption of country are used to find the relationship between economic development and power consumption.
• It is used to find the energy demand for targeted economic development.

d.Mathematical formula:

• Incremental formula

P=P_o(1+(R/100))ⁿ

Where,

P= Power demand after n year

P_o= Power demand at present

R= Incremental rate of power demand

1.6 Load curve

• It is a graphical representation of power consumption with respect to time.
• It may be daily, weekly, monthly or annual.
• 1 unit = 1 KWhr
  • Base load= Minimum power demand in given time duration
  • Peak load= Maximum power demand in given time duration
  • Average load= Average power consumption in defined time period

i.e Average load= (Area under curve/Total duration of time)

Load factor (LF):

• It is defined as the ratio of average load by peak load. i.e LF=Average load/Peak load

Utilization factor (UF):

• It is defined as the ratio of peak load by installed capacity. i.e UF=Peak load/Installed capacity

Diversity factor (DF):

• It is defined as the ratio of the sum of maximum demand to the maximum demand of entire system. i.e DF= Sum of maximum demand/Maximum demand of entire system

1.7 Power demand variation

• Power demand variation is the fluctuation of electrical power demand over time.
• This variation can be characterized by:-

a.Daily variation of power:

• Maximum demand in morning and evening.
  • Less demand during office hours.

b. Weekly variation of power:

• More stable than daily variation.
• Weekends tends to have lower energy demand than weekdays.

            c. Monthly variation of power:

• More demand during festival in different months.

            d. Annual variation of power:

• Different season in year have different demand.
• During winter we require power for heating.
• During summer we use electricity for cooling.

1.8 Power grid

• It is a system of interconnected power plants, transmission lines and distribution networks that are used to deliver electricity from the power plants to homes and businesses.
• It is also responsible for ensuring electricity generated is used efficiently and safely.

Components of power grid system:

1. Dam:

• Used to store water and regulate the flow of water into the turbine.

2.Turbine:

• Used to convert the kinetic energy of water into electrical power.

3. Generator:

• Used to convert mechanical power generated by the turbine into electrical power.

4.Transmission line:

• Used to transport the electrical power generated by the generator to the consumers.

5.Control system:

• Used to regulate the flow of water and flow of electrical power in the system.

References:

• Hydropower Development: Engineering & Policy Perspectives – John S. Gulliver & Roger E. A. Arndt
• Renewable Energy Systems: Hydropower and Beyond – Godfrey Boyle

The post Power and energy potential study appeared first on OnlineEngineeringNotes.

Hydropower project planning stages is divided into three main categories:-

1. Reconnaissance

• It is first stage of project planning.
• It is mainly based on secondary data from maps, aerial photographs and visual inspection.
• This is done mainly for license acquisition purpose.

Objective:

• To identify the suitable project for the stated purpose.
• To provide preliminary cost figure of the project.

Major steps are:-

• Data collection
• Desk studies
• Field work and design
• Estimation
• Environmental and social studies
• Economic assessment
• Report

2. Prefeasibility

• In prefeasibility study the review of the study made in reconnaissance studies is further studied in detail from precise instrument, data series of long time and field survey data.

Objective:

• Establish the need and justification for the project.
• Formulate the plan for developing the project.
• Determine the technical, economic and environmental practicability of the project.
• Make recommendation for further action.

Major steps are:-

• Data collection
• Desk studies
• Field work and design
• Estimation
• Environmental and social studies
• Economic assessment
• Report

3. Feasibility

• In this level pf study the detailed study of the project is carried out in order to determine the technical, economic and environmental feasibility of the project.

Objective:

• To carry out detail design of the project.
• To direct project towards construction.

Major steps are:

• Data collection
• Desk studies
• Field work and design
• Estimation
• Environmental and social studies
• Economic assessment
• Report

1.2 Hydrological data processing

a. Mass curve:

• It is a graph of cumulative values of a water quantity (runoff) against time.
• Also known as Ripple curve.
• It is and integral curve of a hydrograph.

Characteristics:

• It is continuously rising curve.
• The slope at any point on the curve represent the inflow rate.
• If the curve rises sharply, it indicates the high rate of inflow within that period.
• If the curve is horizontal, the flow is zero.
• If the curve is convex, it indicates flood.

Uses:

• It helps in designing the size of the storage required for hydro-electric power plant.
• Check the consistency of many kinds of hydrologic data.

b. Flow Duration Curve (FDC):

• It is the plot of discharge versus percentage of time exceedance of discharge.

Characteristics:

• The slope of flow duration curve depends upon the interval of the data.
• FDC is a decreasing curve.
• Chronological sequence is disturbed in flow duration curve.
• With the increase in storage, the flow duration curve becomes flatter.
• Area under flow duration curve gives flow volume.

Use:

• It is useful in planning and designing of water resource projects.
• It helps in the design of drainage system and in the flood control studies.

1.3 Reservoir planning and regulation

Reservoir:

• When a barrier is constructed across the river, the pool of water formed on the upstream side of the barrier is called reservoir.

Classification of reservoir:

1. Flood control reservoir

• Main purpose of the reservoir is to temporarily store the flood water and release slowly at a safe rate.
• Gates and spillways are used for flood control.

2. Storage or conservation reservoir

• Used to maintain minimum supplies of water for irrigation, hydropower and industries.
• Used to store excess water.

3. Distribution reservoir

• Small capacity reservoir used to fulfill the water supply requirement of a particular city.
• Made of masonry or cement concrete.

4. Multipurpose reservoir

• Reservoir planned and designed for more than one purpose.
• Used to protect from flood, irrigation, water supply and hydroelectric purpose.

Site selection for reservoir:

• Should be located in area with maximum inflow and minimum percolation.
• Site should be accessible by road.
• Site should be located at narrow opening of the basin.
• Construction materials for the dam should be available locally.
• Site should have sufficient water depth.
• Site should be free from objectional minerals.

Regulation of reservoir:

• It is defined as the rational distribution of river flow in time and space among different fields of water resource system.

Need of reservoir regulation:

• The hydroelectric plant will not operate with efficiency if it is operated be low certain head.
• To prevent the excessive siting in the reservoir.

Useful life of reservoir:

• It is impossible to completely stop the flow of sediments of water into reservoir. A dead storage is made available to accommodate the volume of sediments.
• The useful life of reservoir is said to exist till the storage is reduced to 20% of designed capacity.

1.4 Environmental study policy based on type and size

• In order to check whether the proposed project has significant effect on the environment and whether such effect could be avoided or mitigated by any means or not, various studies are carried out at different stages of project planning which is known as Environmental Assessment (EA).
• There are two types of environmental study policy:
  • IEE (Initial Environmental Examination)
  • EIA (Environmental Impact Assessment)

Process of EIA/IEE:

1. Environmental screening:
   • Process determine whether EIA or IEE is required or not.
2. Scoping:
   • Purpose of scoping is to gather and identify the matters which should be covered in environmental information submitted to concerned authority.
   • Involvement of relevant authorities, affected groups.
   • Identification of relevant or significant issues to examined.
3. TOR (Terms of Reference):
   • Provides basic guideline to conduct project specific EIA or IEE.
4. EIA/IEE Report:
   • For IEE it is review by MOEn(Ministry of energy) and approved.
   • EIA is review by MOEn and approved by MOEST (Ministry of Environment, Science and Technology).

1.5 Climate change and ecology:

River Engineering:

• In Himalayan area discharge of river is low and velocity is also low but in plain area discharge is high and velocity is low. So, this leads to sedimentation of structure and to prevent this various river training structure like guide bank is required.

Social cost:

• Hydropower projects becomes barrier to aquatic life.
• Due to large hydraulic structure it changes the flow regime of river.
• Hydropower project may affect particular social group of the community.

Population displacement:

• Destroys forest, wildlife habitat, agricultural land area by flooding.

Change in lifestyle:

• Pollution
• Health issue

Global worry:

• Global warming due to deforestation
• Destroy vegetation and agriculture

Clean energy alternatives:

• Solar energy
• Wind energy
• Geothermal energy

References:

• Hydropower Development: Engineering & Policy Perspectives – John S. Gulliver & Roger E. A. Arndt
• Renewable Energy Systems: Hydropower and Beyond – Godfrey Boyle

The post Planning and Investigation of Hydropower Projects appeared first on OnlineEngineeringNotes.