Introduction to Electrical Power
Systems
By Prof. Yasmin Sayeed
Anjuman College of Engg. & Tech.,Nagpur
The basic Need of life is Electricity
All works is related to Electricity only
Eg : Electric locomotives, Heating, Cooling, Fans,
Blowers, Motors, Illumination are some applications that
converts electrical energy into useful work.
Growth of any country is measured in terms of per
Capital consumption of Electrical energy.
India’s Consumption of Electricity is - 500 KWH /person
per year
Various Reasons for the Popularity of electricity are :-
Clean environment for user
Higher efficiency
Better controllability
Quick transfer of power from source to load
Energy conservation is simple
Power Generation by different power plants
are in India
Thermal Power --- 1,00,000MW
Hydro Power --- 65,000MW
Nuclear Power --- 10,000MW
Other sources --- 20,000MW
Total Installed Capacity--- 1,95,000MW
Conventional & Non Conventional Sources Of
Electrical Power Generation
A. Conventional Sources
Thermal (Coal)
Nuclear
Gas
Water
B. Non conventional Sources
Wind
Solar- PV
Biomass
Generator
Single Line
Representation 10 to 30 KV
of Step-up T/F
Power System
132 KV, 220 KV, 400 KV.
Transmission EHV
Step down T/F
66 KV, 33 KV OR 11 KV
Distribution HV Receiving
Station
Step Down
To large Industries at 11 kv or 33 kv or
T/F
66 kv
consumer of HV level
440V (Utilization)
Consumers of LV level
Block Diagram Of Coal Fired Thermal Plant
Thermal Power Plant
India has rich stock of coal as natural resource.
Chemical energy stored in coal is transformed to
electrical energy.
Coal powder is fired in boiler that converts water into
steam at high temp. and pressure.
This steam is injected over the blades of steam turbine
(prime mover) in controlled way and hence, rotor of 3
PH a.c. generator rotates.
Mechanical energy is converted into electrical energy at
rated voltage(10-30KV).
Used steam is cooled down to water using cooling towers
and condensers.
This preheated water is again injected in boiler tubes to
convert back to steam.
Flue gases are passed into atmosphere and fine particles of
ash are collected through ESP.
Ash(40% of coal weight) is collected and transported to AHP.
Advantages :
Fuel used is cheaper
Smaller space is required compared to hydro power plant
Thermal plants can be placed near load centers unlike hydro
and nuclear plants. Hence transmission of power losses can
be minimized
Thermal plants are able to respond to the load demand more
effectively and supports the performance of the electrical grid
Demerits of Coal Thermal plant
Pollution of the atmosphere
Huge requirement of water
Handling of coal and disposal of ash is quite difficult and
requires large area
Gestation period (period for commissioning of plant) takes
long time
Efficiency of thermal plant is quite less (30-35%)
Operational cost of thermal plant is more costlier compared
to hydro and nuclear plant
Nuclear Thermal Power Plant
Huge amount of thermal energy is produced through
Nuclear Fusion and Fission process of radioactive
elements.
This thermal energy is used to produce steam that can
be utilized to rotate the turbine coupled to 3 PH a.c.
generator.
Fusion is the process in which two light weight nuclei
combine to produce heavier nucleus, a neutron and lot
of exothermic energy.
Block Schematic for Nuclear Power Plant
Advantages of Nuclear Power Generation
Less quantity of fuel for generation of given amount of
energy compared to other sources.
High reliability, Efficient and less running cost.
Disadvantages of Nuclear Power Generation
Fuel is expensive and not available in abundance
everywhere.
High capital cost.
Maintenance cost is very high.
Nuclear waste disposal is a great problem.
Block Schematic for Hydroelectric Power
Plant
Hydro-electric power is generated by the flow of water
through turbine, turning the blades of the turbine.
A generator shaft connected to this turbine also rotates and
hence generates electricity.
The main components of a hydel power plant are:
• 1. Dam/Reservoir/Large buffer tank
• 2. Penstock
• 3. Power House
• a. Turbines
• b. Generators
• c. Step-up Transformers
Depending on the capacity, hydel power plants
are divided into the following categories :
Hydel plants are normally not in a continuous operation mode and
used for peak periods during the day like the wee hours and in the
evening.
Also, they are used when the continuously operating thermal plants
go into overhauling.
This is possible due to the less start up time required by hydro
power stations which is normally in few minutes as compared to
thermal power plant which is more than 8 hours.
The command for starting or shutting is issued by from the related
Load Dispatch Center (LDC) of that particular region
Hydel plants have an efficiency of 75%.
The power delivered is given by the following
expression:
Power delivered = 7*H*dQ/dt Kilo watts,
Where,
H = Head in meters
dQ/dt = Rate of discharge in m3/s.
Advantages of Hydro Power Generation
Once a dam is constructed, electricity can be produced
at a constant rate
If electricity is not needed, the sluice gates can be shut,
stopping electricity generation
The build up of water in the lake means that energy can
be stored until needed, when the water is released to
produce electricity.
The lake's water can be used for irrigation purposes.
Hydropower is fueled by water, so it's a clean fuel
source. Hydropower doesn't pollute the air like power
plants that burn fossil fuels, such as coal, oil or natural
gas.
Disadvantages of Hydro Power Plant
Dams are extremely expensive to build and must be built to a very
high standard.
People living in villages and towns that are in the valley to be
flooded, must move out.
Hydro power plants can be impacted by drought. When water is not
available, the hydro power plants can't produce electricity.
Block Schematic for Wind Power Plant
wind DC/DC DC/AC
rectifier utility line
generator converter inverter
The grid-connected application
wind DC/DC DC/AC AC load
rectifier
generator converter inverter
DC-DC DC load
Converter
battery
The stand-alone application
Wind Generator
Solar Energy
Applications
Solar Water Heating : Solar energy can be used to
heat water. A solar water heater works a lot like solar
space heating. A solar collector is mounted on the roof
where it can capture sunlight.
Advantages of Solar Energy Systems
After initial investment, all the electricity produced is free.
Incentives and rebates from government and utility
companies offset the initial investment.
Clean, renewable energy source.
No transmission costs for stand alone systems.
Virtually no maintenance and no recurring costs
Ideal for remote locations that cannot be tied to the grid
Solar Energy Disadvantages
High initial cost to purchase solar panel system
A relatively large area is required to install a solar system
The highest efficiency is dependent on full sun exposure
No electricity can be produced at night, and reduced production on cloudy/rainy days
