Introduction to Power System Operation

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Introduction to Power SystemOperation

Power Generation and Economics


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Power Generation

Fundamental of Energy Source Power System Behavior Energy Transfer in Power System

Economics Maximum Demand, Demand Factor Diversity Factor

Plant Capacity Factor Annual Plant Use Factor Load Sharing Between Generating Station


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Fundamental of Electric Source : Theory ofPower Generation

Associated very close to Left Hand Rule

Magnetic flux

N S

Cutting the flux lines

Induce current


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Steam pushes theturbine blades

Blades cut throughmagnetic flux

Current induced;

electric produced


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Steam generation

Steam is a vaporized air with certain speed, andtemperature

It contains a lot of energy and circulates inside

Rankine Cycle.

It is resulted from energy changing from one form toanother


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General arrangement of fossil fuel facility


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High pressure and high temperature stream rotatesteam turbine and generate electric power


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As steam rotates turbine, it loses energy. And asresult its pressure and temperature are greatlyreduced


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The steam is then changed into liquid (water) bya condenser. Condenser eliminates heat into itssurrounding


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Liquid is the goes into compressor inlet to regainhigh pressure.


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High pressure water is added with hightemperature through boiling process. Fuel (coal/nuclear) boils the high pressured water


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High temperature and pressure steam produced,and rotates turbine to generate electric power


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Spin the turbineat prime move(excl. solar

direct

conversion type)

Generateelectric powerby flux rotationin function of

time

V = N (d / dt)

Energy Sources

Common andtraditionalConventional

Source

Also known

as renewableenergy sourceGreenSource


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Source ofenergy

Conventional

Coal

Nuclear

Water

Renewable

Solar

Wind

Biofuels

Oceantemperature


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Source ofenergy Turbine

Transmission

lineLoad

Source ofenergy

Rotation ofturbine

( 2 f)

Generatorexcitation currentic increase flux,

Increasevoltage V = N

(d / dt)

Produce electricpower

To load throughtransmission

line


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Energy Transfer in Power System

Combustion of coal, rapid movement of water,pressurized gas / steam, produce energy to spin theturbine

Spin of turbine generates electric power

However, for large and high concentrated areasneed power stability. Combined cycle or coal arepreferred. Hydro and solar are usually ruled out.


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At the event of massive load reduction, generatorsense increase of voltage

Turbine has to slow down the rotation to limit outputTo limit rotation, frequency of turbine needs to bereduced

Massive load increase, generator sense reduction ofvoltageTurbine needs to increase rotation to produceincrease inputFrequency of turbine to be increase


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However, under both circumstances, changes ofvoltage/ frequency produce oscillations

This oscillation needs to be managed for the systemto return to stability condition

Management of oscillations requires collaborationsof power system parameters (security,communication, etc)


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Energy transfer using steam/gas

Boilers (place of combustion coal, gas, oil) producesteam at high temperature and pressure

Steam goes into turbines. Spinning turbines results

in electric power.

Rankine cycle is preferred (modified to include superheating, feed water heating, and steam reheat


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Coal Fired Power Plant (Steam/Gas)


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Nuclear Power Plant (Steam)


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Energy transfer using water

Oldest form of energy conversion

Energy is FREE, thanks to gravity and water atomicbuilt

However, building hydro power plant need massivecost and must consider geographic surface


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Hydro Power Plant (Water)


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Power available from hydro power plant is calculate-able by (assuming efficiency is 100%):

P = (1.0) gWH (Watt)

Where:

is the density of water = 1000 kg/m 3 g is the gravity rate = 9.81ms -2

H is the Head measured in m (height of

upper water level above lower)W is the flow rate (m 3/s) through turbine


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Example:

Average flow of a river is 575m3/s and type ofdesired turbine is Kaplan. Assuming that the powerto be extract is 100% of the capacity of Kaplanturbine, and efficiency of the system is 100%,determine the power to be developed per cubic

meter per second.

Solution:

Kaplan turbine : 100% capacity = 61m (H up to 61m)Efficiency, n = 100%Water density = 575 m3/sGravitational force = 9.81m/s2


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Pelton

Heads (H) 184m 1840m

Bucket wheel rotorand adjustableflow nozzles

Francis H = 37 490m Mix flow type

Kaplan H = up to 61m Only run of river/

pondage station


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Francis hydro turbine Pelton hydro turbine Kaplan hydro turbine


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Sea tides also can be utilized to produce electricpower. This has been done in Scotland where thewater is rocky and tides are consistently hardthroughout the year

Sea tide produces electric power as :

P = () gh 2 A (Watt) * A = area of waterin water basin


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Energy transfer using solarHuge solar power plant in France produces electricpower through heat radiation

The farm includes thousands of sun light deflectors

which deflect sun light to one tall boiler

Heat generated, in turn is used to produce steam forthe turbines


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Solar Power Plant (Steam/Gas)


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Energy collected from one per square meterdeflector is :

q = I ( F + B) (T4 T40)

I is the incident radiation normal to surface

F and B is the front and back emissivitiesof absorber

is the absorptive of panel is the transmittance of cover plate is the Stefan Boltzmann constant


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Energy transfer through windBy utilizing speed of wind, generation of electricpower is possible

Wind turbine is positioned at the optimum area

where speed and concentration of wind is atmaintained

Stable wind speed is preferred to its high speed


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Higher towers, blades produce high outputs butcomes at extra cost. Power generated by wind is asfollows

P = AU 3 (Watt)

Where

is the air density = 1.201 kg/m 3

U is the air velocity (m/s ) A is the swept area of blade (m)


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TutorialCalculate the number of wind generators required toproduce equivalent of 600MW. Please assume windspeed is 10kmh or 2.78 ms-1, blade diameter is20m, and conversion efficiency is 45%

Given :

Blade diameter, d = 20mWind speed, U = 2.78 ms-1


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Wind power, P can be calculated

P = AU3

= (1.201) ( (20/2) 2) (2.78x10-3)= 4053kW

Since conversion efficiency is at 45%, thus totalpower generated

P = 4053kw x 45% = 1823kW


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Since one wind turbine produce 1823KW, thus toproduce equivalent of 600MW, number of turbineneeded is:

Number of turbine = 600MW / 1823KW= 330 turbine


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TutorialIn a new 25m depth built reservoir, power isgenerated through 5 turbines and is deliveredthrough a transmission line system to support lightlocal load. Due to fluctuation of incoming watersource, minimum water level is recorded at 55% ofmaximum. Determine required power generated perturbine.

Given the water flow rate is 70m3

/s during maximumwater level and 35m 3/s during minimum water level.

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Introduction to Power System Operation