power system operations

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EE 425

POWER SYSTEM

OPERATION

NOVEMBER 2012 ENGR. D. ALPIS


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POWER PLANT

A power stationor power plant is a facilityfor the generation of electric power. 'Power plant'

is also used to refer to the engine in ships,

aircraft and other large vehicles. Some prefer to

use the term energy center because it is moreaccurately describes what the plants do, which is

the conversion of other forms of energy, like

chemical energy, gravitational potential energy or

heat energy into electrical energy.

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POWER PLANT

At the center of nearly all power stations isa generator, a rotating machine that converts

mechanical energy into electrical energy by

creating relative motion between a magnetic field

and a conductor. The energy source harnessed toturn the generator varies widely. It depends

chiefly on what fuels are easily available and the

types of technology that the power company has

access to.

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POWER PLANT ENGINEERING

Art of designing and installing generating

plant that will result in maximum return oninvestment (profit) over the expected life of the

equipment. And also operating this equipment to

achieve reliable, continuous and cheap power

service.

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A station or establishment which houses

the prime-movers, electric generators andauxiliaries, for conversion of mechanical,

chemical and/ or nuclear energy into electrical

energy.

POWER PLANT ENGINEERING


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THERMAL POWER PLANT CLASSIFICATION

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1. By FUEL

a. NUCLEAR POWER PLANTS use a nuclear

reactors heat to operate a steam turbine

generator.


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b. FOSSIL FUEL POWERED PLANTSmay also

used a steam turbine generator or a NATURALGASfired plants may use a combustion turbine.


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c. GEOTHERMAL POWER PLANTSuses steam

extracted from hot underground rocks.


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d. RENEWABLE ENERGY PLANTS maybe

fuelled by waste from sugar cane, municipal solidwaste, landfill or methane or other forms of

Biomass.

2. By PRIME MOVER

a. STEAM TURBINE plants use the pressure

generated by expanding steam to turn the

blades of a turbine.

b. GAS TURBINE plants use the heat from gases

to directly operate the turbine. Natural gasfuelled turbine plants can start rapidly and so

are used to supply "peak" energy during

periods of high demand, though at higher cost

than base-loaded plants.


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c. COMBINED CYCLE plants have both a gas turbine fired

by natural gas, and a steam boiler and steam turbine which

use the exhaust gas from the gas turbine to produce

electricity. This greatly increases the overall efficiency of

the plant, and most new base-load power plants are

combined cycle plants fired by natural gas.

d. Internal combustion Reciprocating Engines are used toprovide power for isolated communities and are frequently

used for small co-generation plants. Hospitals, office

buildings, industrial plants, and other critical facilities also

use them to provide backup power in case of a power

outage. These are usually fuelled by diesel oil, heavy oil,natural gas and landfill gas.


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e. MICROTURBINES, STIRLING ENGINES and

internal combustion reciprocating engines arelow cost solutions for using opportunity fuels,

such as landfill gas, digester gas from water

treatment plants and waste gas from oil

production.


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OTHER SOURCES OF ENERGY

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Other power stations use the energy from

wave or tidal motion, wind, sunlight or the energyof falling water, hydroelectricity. These types of

energy sources are called renewable energy.

Hydro Electric Power Plant an electric

generating station using flowing waters to drive

the prime-movers (hydraulic turbines) either

impulse or reaction type.


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TION TWO TYPES OF HYDRAULIC TURBINES

a) Impulse Type use for high-heads and lowvolume, example is the Pelton wheel.

b) Reaction Type use for low-heads and highvolume, examples are Francis and Kaplan.

TYPES OF HYDRO-ELECTRIC PLANT

a) Run-of-riverusing pondage or steam flow as

it occurs, more power can be generated in a

rainy season than in dry season.

b) Plant with storage capacity associated with a

large water reservoir. This permits regulated

supply of water so that the power output is

constant throughout the year.


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POWER

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TION TYPES OF HYDRO-ELECTRIC PLANT

c) Pump-storage Plant where energy is

generated during periods of high system demandusing water which has been pumped into a

reservoir usually during periods of relatively low

system demands.

3. Diesel Power Plant a plant of internal

combustion engine (ICE) prime-mover using

diesel as fuel in producing energy.

4. Windmill Plant using a series of windmills as

prime-mover.


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TION Types of Power Plant (As to Use)

1. Base-Load Plant plant that assumed load

requirements under normal conditions.

2. Peaking Plant plant that is normally operated

to provide power only during peak load periods.

3. Regulating Plant plant capable of carrying

load for the time interval either during off-peak or

peak periods and usually responds to changes in

system frequency.

4. Reserve or Stand by Plant for peak or system

deficiencies.


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TION TYPES OF PLANT RESERVES

a) Cold Reserveportion of the installed reservekept in operable condition and available forservice but not for immediate loading.

b) Operating Reserve refers to capacity in

actual service in excess of peak loads.

c) Hot reserve refers to units available,

maintained at operating temperature and ready

for service although not in actual operation.

d) Spinning Reserve generating capacity

connected to the bus ready to take load.


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TION THERMAL EFFICIENCY (et)

Heat equivalent of mechanical energy transmitted to the turbinee =

Heat of fuel combustiont

net A R R coldt

A A A hot

W Q - Q Q T= = = 1- = 1-

Q Q Q Te

net t Pwhere : W = W - W

Overall Efficiency (eo)

O

Heat Equivalent of Electrical Output=

Heat of Fuel Combustione


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TION THERMAL EFFICIENCY (et)

O t g= xe e e

where : e = electrical efficiency = alternator efficiencyg

HEAT RATE (HR)

t

1HR = x K

e

where : K = constant conversation factor

Values of K based from the following Conversion Factor

1 KWh = 3600 KJ 1 kWh = 3413 BTU

1 HP hr = 2545 BTU 1 KWh = 860 Kcal.


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TION IMPORTANT TERMS AND PLANT FACTORS:

1. Connected Load (CL) it is the sum of all

continuous rating of all utilization equipment inthe consumer premises connected to the supply

system.

2. Maximum Demand (or Peak Load) (MD) it is the

greatest demand of load on the power stationduring a given period.

3. Average Load (AL) the average of loads

occurring on the power station in a given period,

sometimes called averagedemand.

Total Energy Produced TEP

Average Load AL =Period


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4. Demand Factor (DF) it is the ratio of maximum

demand on the power station to its connected

load.

MDDemand Factor DF = 1.0CL

5. Diversity Factor (Div F) the ratio of the sum of

individual maximum demand to the simultaneous

maximum demand on the power station.

MD's

Div. Factor DF = 1.0simulataneous MD


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6. Coincidence Factor (CO. F) reciprocal of

diversity factor.

simulataneous MD 1Co. Factor Co.F = = 1.0MD's Div. Factor

7.Load Factor (LF) it is the ratio of average load to

the maximum demand during a given period.

r

Average Load TEPL.F. = =MaximumDemand M.D. x S


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8.Capacity Factor (CF) it is the ratio of actual

energy produced to the maximum possible

energy that could have been produced during a

given period.

r

TEPC.F. =

I.C. x P

9.Nameplate or Capacity Rating is the ability to

carry load under conditions specify by the

manufacturer.

10. Capability Rating is the maximum output ofequipment obtained by test under specific

operating condition (not specified by

manufacturer)


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11. Plant Use (or Output) Factor it is the ratio of

the energy generated to the product of plantcapacity and the number of hours for which the

plant was in operation.

r

TEPP.U.F=

I.C. x S

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