Hydroelectric Power Plant Terms

Hydroelectric Power Plant

facility which electric energy is produced by harnessing the hydraulic energy or gravitational force of flowing water

Run of River (Diversion)

channels a portion of a river through a canal or penstock with not requiring the use of a dam

Pondage

collection of water behind a dam at the plant and increases the steam capacity for a short period of time

Storage

collection of in-upstream reservoirs and this increases the capacity of streams over an extended period of time

Run-of-river Plants without Pondage

Doesn't store water and uses as the water comes

Run-of-river Plants without Pondage

No control on the flow of water

Run-of-river Plants without Pondage

Generating capacity depends on the rate of flow of water, meaning dry period water flow rate will be low

Loboc 1.2 MW Mini Hydroelectric Power Plant

an example of a run-of-river plant without pondage

Run-of-river plants with Pondage

plants may work satisfactorily as base load and peak load plants

Run-of-river plants with Pondage

is more reliable and generating capacity is less dependent on flow of water than that of without pondage

Storage-type Plants (Impoundment Plants/Dam Type)

water is stored behind the dam and water is available throughout the year

Storage-type Plants (Impoundment Plants/Dam Type)

has a reservoir of a large size to permit carry over storage from seasons and supply firm flow substantially more than minimum natural flow

Storage-type Plants (Impoundment Plants/Dam Type)

plant can be used as base load plant as well as peak load plant as water can be controlled

San Roque Multipurpose Hydroelectric Power Plant (3x115MW)

utilizes the Agno River for power generation and irrigation and contributes to flood control and water quality improvement in the region

Pumped Storage Plant

employed at places where quantity of water available for power generation is inadequate

Pumped Storage Plant

for peak periods, the water from the reservoir is carried downhill by a penstock that drives the turbine and generator for electricity to meet the increased demand while for off-peak periods, water is pumped back to the reservoir through excess power available

736 MW Kalayaan Pumped Storage Power Plant

first in Southeast Asia and only pumped storage in the Philippines

736 MW Kalayaan Pumped Storage Power Plant

large peaking facility for the Luzon grid and in the daytime, it generates electricity and at night it pumps water from Laguna Lake to Caliraya Reservoir to store energy

Gross Head

difference between the head water level in forebay and tailbay/tailrace

Gross Head

water must fall from a higher elevation to a lower one to release its stored energy

Pelton Turbine (Impulse)

used for high head (400 and above in m) (1300 above in ft)

Pelton/Francis Turbine

used for heads 240-400m or 800-1300ft

Francis Turbine

used for medium head (30-240m or 110-800ft)

Francis/Propeller

used for heads 20-30m or 70-110ft

Propeller Type Turbine (Kaplan)

used for low heads (>20m or >70ft)

345 MW San Roque Hydroelectric PP

large power plant in San Manuel, Pangasinan

4.5 MW Bineng Hydroelectric PP

Mini power plant in La Trinidad, Benguet

Base Load Plants

plants are required to supply constant power

Base Load Plants

run continuously without any interruption and mostly remote controlled

Base Load Plants

examples are storage plants or run-off river plants without pondage

Peak load plants

plants which supply the power at peak load

Peak load plants

only work during certain hours of a day when load is more than the average

Isolated (off-grid) power plants

set up in a remote area to meet local demands

Interconnected (on-grid) power plants

set up to meet demands of areas which area a fair distance from the plant

Single Purpose

whole soul purpose is to produce electricity

Multi-Purpose

water used in the project is used for other purposes such for generation of electricity, irrigation of agricultural land, flood control, fisheries and tourism, and domestic water supply

Single Stage

when the run off is diverted back into the river for another purpose other than power generation

Cascade Stage

two or more hydropower plants connected in series such that the runoff of one is used as intake of the second plant

Forebay

basin area where water is temporarily stored before going into intake chamber

Intake Structure

structure which collects water from the forebay and directs it into penstocks using trash racks (trap debris in the water), rakes and trolley arrangement (clean the trash racks), and closing gates

Penstock

are like large pipes laid from some slope which carries water from intake structure to turbines

Penstock

either embedded or buried in concrete dam or exposed above the ground

Surge Chamber / Surge Tank

cylindrical tank usually provided in high or medium head plants with long penstock

Surge Chamber / Surge Tank

provides excess water needed when the gates are suddenly opened for higher load demands

Surge Chamber / Surge Tank

for a sudden reduction in load, governor closes the gates to reduce the flow and the surge tank rises the water level to reduce the pressure

Hydraulic Turbine

device that convert hydraulic energy into mechanical energy

Power House

building provided to protect the hydraulic and electrical equipment

Draft Tube

connects the turbine outlet to the tailrace

Draft Tube

contains gradually increasing diameter so that the water discharged into the tailrace with safe velocity

Tailrace

carry away the water discharged from turbine after power is produced from the water

Impulse Turbine

runner/wheel passages are never completely filled with water

Impulse Turbine

kinetic energy in water leaving the nozzle and entering the runner with atmospheric pressure

Pelton Wheel

tangential flow impulse type water turbine created by Lester Allan Pelton in 1870s

Pelton Wheel

wheel with a set of buckets or double cups around the rim wherein the water passes round the curved bowls and gives up almost all its kinetic energy

Pelton Wheel

useful turbine for high hydraulic heads and low flow rates of the water source

Turgo Turbine

invented by Eric Crewdson in 1919 by Gilkes

Turgo Turbine

modification of the Pelton Wheel wherein the double cups are replaced by single, shallower ones with water entering on one side and leaving on the other

Cross-Flow Turbine

also known as Banki-Michell and Ossberger

Cross-Flow Turbine

water enters a flat sheet rather than a round jet, which is guided on to blades and travels across the turbine to meet the blades again as it leaves

Reaction Turbines

runner is completely filled with water under a pressure which varies throughout the flow

Reaction Turbines

energy is partly pressure and partly kinetic

Francis Turbine

developed by James B Francis

Francis Turbine

most common type in plants which are considered as radial-flow turbines (flow is inwards towards the center)

Kaplan and Propeller Turbine

propeller-type water turbine with adjustable blades discovered by Viktor Kaplan in 1913

Kaplan and Propeller Turbine

uses axial flow wherein the water flows through the runner along the direction parallel to the axis of rotation of runner

Kaplan and Propeller Turbine

evolution of the Francis turbine that allowed efficient power production in low-head applications

Nozzle

used to form the high speed water jet

Needle Spear

arranged inside the nozzle to control the water jet from nozzle

Needle Spear

moved forward to reduce flow and backward to increase flow

Runner

circular disc on the periphery of which a number of buckets are mounted

Splitter

provided for each bucket to separate it into two equal parts

Casing

covers the whole arrangement and prevents the splashing of water while working and helps the water to discharge to the tail race

Breaking Jet

used to stop the running wheel when not working

Breaking Jet

jet directed by brake nozzle on the back of buckets to stop the wheel

Jet Deflector

diverting the water flow between the nozzle in a way that it does not hit the buckets

Jet Deflector

used for emergency stops or regulating the turbine and prevent over speeding

Spiral Casing

inlet medium of water to the turbine

Spiral Casing

the diameter is gradually reduced to maintain uniform pressure in the circular movement of water

Stay Vanes

fixed panels that receives pressurized water from spiral case and directs to wicket gates

Stay Vanes

installed to reduce the swirling of water due to radial flow

Guide Vanes or Wicket Gates

also regulate flow rate of water into runner blades thus controlling the power output of a turbine according to the load on the turbine

Guide Vanes or Wicket Gates

change their angle as per the requirement to control the angle of striking of water to turbine blades to increase the efficiency

Draft Tube

pipe of gradually increasing area which connects the outlet of the runner to the tailrace

Draft Tube

permits a negative head to be established and increase the net head on the turbine

Draft Tube

turbine may be placed above the tailrace without loss of net head for proper inspection

Draft Tube

converts a large proportion of kinetic energy rejected at turbine outlet into useful pressure energy instead of going to waste

Spiral Casing

spiral type of casing with decreasing cross section area

Spiral Casing

protects the runner, runner blades, guide vanes and other parts of turbine from external damage

Runner Blades

rotating part which helps in production of electricity. The shaft is connected to the generator shaft

Runner Blades

runner of the blade has a large boss on which its blades are attached and the blades is adjustable to an optimum angle of attack for maximum power output

Frictional Power (FP)

power used up in overcoming mechanical friction in bearings and stuffing boxes and disk friction between sides of rotor and fluid in the adjacent casing

Specific Speed (NS)

used to characterize the operation of a turbine at its optimum conditions and useful for preliminary turbine selections

2-10

Specific Speed Range of Impulse (Pelton)

20-100

Specific Speed Range of Francis

80-200

Specific Speed Range of Kaplan

Classification of Hydroelectric Power Plants

Capacity of Water Flow Regulation; Availability of Head; Power Plant Capacity; Nature of Load Characteristics; Based on Transmission System; Purpose; Hydrological Relation

Major Components of Hydroelectric Power Plant

Forebay; Intake Structure; Penstock; Surge Chamber/Tank; Hydraulic Turbine; Power House; Draft Tube; Tailrace

Types of Impulse Turbines

Pelton Wheel; Turgo Turbine; Cross-Flow Turbine

Types of Reaction Turbines

Francis; Kaplan

Main Components of Impulse Turbine Pelton Wheel

Nozzle and Flow Regulating Arrangement; Runner and Buckets; Casing; Breaking Jet; Jet Deflector