Module 5 HYDROPOWER ENGINEERING LESSON 2 HYDROPOWER WATER CONVEYANCE SYSTEM Notes | EduRev

Created by: Piyush Kaul

: Module 5 HYDROPOWER ENGINEERING LESSON 2 HYDROPOWER WATER CONVEYANCE SYSTEM Notes | EduRev

 Page 1


 
 
 
 
 
 
 
Module 
5 
  
HYDROPOWER 
ENGINEERING 
Version 2 CE IIT, Kharagpur 
 
Page 2


 
 
 
 
 
 
 
Module 
5 
  
HYDROPOWER 
ENGINEERING 
Version 2 CE IIT, Kharagpur 
 
 
 
 
 
 
 
 
LESSON  
2 
 
HYDROPOWER WATER 
CONVEYANCE SYSTEM  
 
 
Version 2 CE IIT, Kharagpur 
 
Page 3


 
 
 
 
 
 
 
Module 
5 
  
HYDROPOWER 
ENGINEERING 
Version 2 CE IIT, Kharagpur 
 
 
 
 
 
 
 
 
LESSON  
2 
 
HYDROPOWER WATER 
CONVEYANCE SYSTEM  
 
 
Version 2 CE IIT, Kharagpur 
 
As indicated in Lesson 5.1 a dam or diversion structure like a barrage obstructs the flow 
of a river and creates a potential head which is utilized by allowing the water to flow 
through the water conducting system upto the turbines driving the generators and then 
allowing it to discharge into the river downstream. Right from the intake of the water 
conducting system, where water enters from the main river, up to the outlet where water 
discharges off back into the river again, different structural arrangements are provided 
to fulfil certain objectives, the important ones being as follows: 
1. The water inflowing into the conveyance system should be free from undesirable 
material, as far as possible, that may likely damage the turbines or the water 
conducting system itself. 
2. The energy of the inflowing water may be preserved, as far as possible, 
throughout the water course so that the turbine-generator system may extract the 
maximum possible energy out of the flowing water. 
As an example of the first case, it may be cited that in hilly rivers, there are good 
chances of sand, gravel, and even boulders getting into the water conducting system 
along with the flowing water. The bigger particles may choke the system whereas the 
smaller ones may erode the turbine blades by abrasive action. Apart from these, floating 
materials like trees or dead animals and in some projects in the higher altitudes ice 
blocks may get sucked into the system which may clog the turbine runners. 
The main components of a water conveyance system consists of the following: 
1. Intake structure 
2. Water conducting system comprising of different structures 
3. Outflow structure, which is usually a part of the turbine tail end 
The water conducting system, again, may be of two types 
1. Open channel flow system 
2. Pressure flow system 
In the pressure flow system, there could be further classification into the two types, as: 
1. Low-pressure conduits and tunnels 
2. High-pressure conduits, commonly called the penstocks 
 
In either of the above cases, some provision is usually made to prevent the undesirable 
effects of a power rejection in the generator that may cause the turbine to spin 
exceedingly fast, resulting in a closure of the valves controlling the flow of water at the 
turbine end. If the closure is relatively fast, high pressures may develop in pressured 
systems conducting water to the turbine. For open channel systems, this may lead to 
generation of surges in the water surface which may even cause spillage of the channel 
banks if adequate freeboard is not provided. 
This chapter discusses the important issues related to the different components of a 
hydropower Water Conveyance System. 
Version 2 CE IIT, Kharagpur 
 
Page 4


 
 
 
 
 
 
 
Module 
5 
  
HYDROPOWER 
ENGINEERING 
Version 2 CE IIT, Kharagpur 
 
 
 
 
 
 
 
 
LESSON  
2 
 
HYDROPOWER WATER 
CONVEYANCE SYSTEM  
 
 
Version 2 CE IIT, Kharagpur 
 
As indicated in Lesson 5.1 a dam or diversion structure like a barrage obstructs the flow 
of a river and creates a potential head which is utilized by allowing the water to flow 
through the water conducting system upto the turbines driving the generators and then 
allowing it to discharge into the river downstream. Right from the intake of the water 
conducting system, where water enters from the main river, up to the outlet where water 
discharges off back into the river again, different structural arrangements are provided 
to fulfil certain objectives, the important ones being as follows: 
1. The water inflowing into the conveyance system should be free from undesirable 
material, as far as possible, that may likely damage the turbines or the water 
conducting system itself. 
2. The energy of the inflowing water may be preserved, as far as possible, 
throughout the water course so that the turbine-generator system may extract the 
maximum possible energy out of the flowing water. 
As an example of the first case, it may be cited that in hilly rivers, there are good 
chances of sand, gravel, and even boulders getting into the water conducting system 
along with the flowing water. The bigger particles may choke the system whereas the 
smaller ones may erode the turbine blades by abrasive action. Apart from these, floating 
materials like trees or dead animals and in some projects in the higher altitudes ice 
blocks may get sucked into the system which may clog the turbine runners. 
The main components of a water conveyance system consists of the following: 
1. Intake structure 
2. Water conducting system comprising of different structures 
3. Outflow structure, which is usually a part of the turbine tail end 
The water conducting system, again, may be of two types 
1. Open channel flow system 
2. Pressure flow system 
In the pressure flow system, there could be further classification into the two types, as: 
1. Low-pressure conduits and tunnels 
2. High-pressure conduits, commonly called the penstocks 
 
In either of the above cases, some provision is usually made to prevent the undesirable 
effects of a power rejection in the generator that may cause the turbine to spin 
exceedingly fast, resulting in a closure of the valves controlling the flow of water at the 
turbine end. If the closure is relatively fast, high pressures may develop in pressured 
systems conducting water to the turbine. For open channel systems, this may lead to 
generation of surges in the water surface which may even cause spillage of the channel 
banks if adequate freeboard is not provided. 
This chapter discusses the important issues related to the different components of a 
hydropower Water Conveyance System. 
Version 2 CE IIT, Kharagpur 
 
5.2.1 Intakes 
 
An intake is provided at the mouth of a water conveyance system for a hydropower 
project. It is designed such that the following points are complied, as far as possible: 
1. There should be minimum head loss as water enters from the reservoir behind a 
dam or the pool behind a barrage into the water conducting system. 
2. There should not be any formation of vortices that could draw air into the water 
conducting system. 
3. There should be minimum entry of sediment into the water conducting system. 
4. Floating material should not enter the water conducting system. 
The position and location of an intake in a hydropower project would generally depend 
upon the type of hydropower development, that is, whether the project is of run-of-river 
type or storage type. For each one of these hydropower projects, there are a few 
different types, the important ones of which are explained in the following paragraphs. 
  
Run-of-river type intake 
• Intakes adjacent to a diversion structure like a barrage. Here, an intake for a tunnel is 
placed upstream of the diversion structure to draw water from the pool (Figure 1). For 
a canal intake (Figure 2), the head regulator resembles that of an irrigation canal 
intake. It may be observed from Figure 3 that the canal conveying water, also called 
the power canal, leads to a Forebay before leading to the turbine unit. The exit 
passage from the turbines is called the Tail Race Channel. There is also a Bye-Pass 
Channel to release water when the turbines shut down suddenly.  
 
 
Version 2 CE IIT, Kharagpur 
 
Page 5


 
 
 
 
 
 
 
Module 
5 
  
HYDROPOWER 
ENGINEERING 
Version 2 CE IIT, Kharagpur 
 
 
 
 
 
 
 
 
LESSON  
2 
 
HYDROPOWER WATER 
CONVEYANCE SYSTEM  
 
 
Version 2 CE IIT, Kharagpur 
 
As indicated in Lesson 5.1 a dam or diversion structure like a barrage obstructs the flow 
of a river and creates a potential head which is utilized by allowing the water to flow 
through the water conducting system upto the turbines driving the generators and then 
allowing it to discharge into the river downstream. Right from the intake of the water 
conducting system, where water enters from the main river, up to the outlet where water 
discharges off back into the river again, different structural arrangements are provided 
to fulfil certain objectives, the important ones being as follows: 
1. The water inflowing into the conveyance system should be free from undesirable 
material, as far as possible, that may likely damage the turbines or the water 
conducting system itself. 
2. The energy of the inflowing water may be preserved, as far as possible, 
throughout the water course so that the turbine-generator system may extract the 
maximum possible energy out of the flowing water. 
As an example of the first case, it may be cited that in hilly rivers, there are good 
chances of sand, gravel, and even boulders getting into the water conducting system 
along with the flowing water. The bigger particles may choke the system whereas the 
smaller ones may erode the turbine blades by abrasive action. Apart from these, floating 
materials like trees or dead animals and in some projects in the higher altitudes ice 
blocks may get sucked into the system which may clog the turbine runners. 
The main components of a water conveyance system consists of the following: 
1. Intake structure 
2. Water conducting system comprising of different structures 
3. Outflow structure, which is usually a part of the turbine tail end 
The water conducting system, again, may be of two types 
1. Open channel flow system 
2. Pressure flow system 
In the pressure flow system, there could be further classification into the two types, as: 
1. Low-pressure conduits and tunnels 
2. High-pressure conduits, commonly called the penstocks 
 
In either of the above cases, some provision is usually made to prevent the undesirable 
effects of a power rejection in the generator that may cause the turbine to spin 
exceedingly fast, resulting in a closure of the valves controlling the flow of water at the 
turbine end. If the closure is relatively fast, high pressures may develop in pressured 
systems conducting water to the turbine. For open channel systems, this may lead to 
generation of surges in the water surface which may even cause spillage of the channel 
banks if adequate freeboard is not provided. 
This chapter discusses the important issues related to the different components of a 
hydropower Water Conveyance System. 
Version 2 CE IIT, Kharagpur 
 
5.2.1 Intakes 
 
An intake is provided at the mouth of a water conveyance system for a hydropower 
project. It is designed such that the following points are complied, as far as possible: 
1. There should be minimum head loss as water enters from the reservoir behind a 
dam or the pool behind a barrage into the water conducting system. 
2. There should not be any formation of vortices that could draw air into the water 
conducting system. 
3. There should be minimum entry of sediment into the water conducting system. 
4. Floating material should not enter the water conducting system. 
The position and location of an intake in a hydropower project would generally depend 
upon the type of hydropower development, that is, whether the project is of run-of-river 
type or storage type. For each one of these hydropower projects, there are a few 
different types, the important ones of which are explained in the following paragraphs. 
  
Run-of-river type intake 
• Intakes adjacent to a diversion structure like a barrage. Here, an intake for a tunnel is 
placed upstream of the diversion structure to draw water from the pool (Figure 1). For 
a canal intake (Figure 2), the head regulator resembles that of an irrigation canal 
intake. It may be observed from Figure 3 that the canal conveying water, also called 
the power canal, leads to a Forebay before leading to the turbine unit. The exit 
passage from the turbines is called the Tail Race Channel. There is also a Bye-Pass 
Channel to release water when the turbines shut down suddenly.  
 
 
Version 2 CE IIT, Kharagpur 
 
 
 
 
 
Version 2 CE IIT, Kharagpur 
 
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