Components of Electrical Power Systems
Transcript of Components of Electrical Power Systems
Asst.Prof.Dr.Reza SIRJANI
Components of Electrical
Power Systems
Introduction
Power and Energy are buzz words in today’sworld.
Electricity is emerged as basic necessity withFood, Shelter and Clothing for human being.
Life without electricity has become highlyunimaginable.
Electric locomotives, Heating, Cooling, Fans,Blowers, Motors are some applications thatconverts electrical energy into useful work.
Introduction
Reasons of Popularity of Electricity:
Clean environment for user
Higher efficiency
Better controllability
Quick transfer of power from source to load
Energy conservation is simple
Introduction
Power engineering, also called power systems
engineering, is a subfield of electrical
engineering that deals with the generation,
transmission and distribution of electric power as
well as the electrical devices connected to such
systems including generators, motors and
transformers.
Introduction
Different Fields of Power Engineering
and their related courses in EMU:
Electric Machinery (EENG350 , EENG453)
Power Systems (EENG456, EENG457, EENG458)
High Voltage Engineering (EENG451)
Power Electronics (EENG441,EENG442)
Basic Structure of Power Systems
A power system is an interconnected network
with components converting nonelectrical
energy continuously into the electrical form and
transporting the electrical energy from
generating sources to the loads/users.
A power system serves one important function
and that is to supply customers with electricity
as economically and as reliably as possible.
Power System Components
Power System Components
Generation : Generating and/or sources of
electrical energy.
Transmission: Transporting electrical energy
from its sources to load centers with high
voltages (115 kV and above) to reduce losses.
Distribution : Distributing electrical energy
from substations (11 kV ~ 44 kV) to end
users/customers.
Power System Components
At power generating station (generating
voltage) 11 – 20kV and frequency of 50
Hz
Transform to higher voltage (transmission
voltage) 132kV, 275kV and 400kV
Transform to lower voltage (distribution
voltage) 66kV , 33kV or 11kV
The generator converts nonelectrical energy to
electrical energy. The devices connecting
generators to transmission system and from
transmission system to distribution system are
Transformers.
The main transformers functions are stepping
up the lower generation voltage to the higher
transmission voltage and stepping down the
higher transmission voltage to the lower
distribution voltage.
The main advantage of having higher voltage in
transmission system is to reduce the losses in
the grid.
Since transformers operate at constant power,
when the voltage is higher, then the current has
a lower value.
Therefore, the losses, a function of the current
square, will be lower at a higher voltage.
Power System Components
Power System
Generation
Sources Of Elec. Power Gen.
A.Conventional SourcesThermal (Coal)NuclearGasWater
B.Non conventional SourcesWindSolar- PVBiomass
Power Generation
Disadvantages Of Conventional Sources :
Fossil fuels shall be depleted, forcing us to
conserve them and find alternative resources.
Toxic, Hazardous gases, Residues pollute
environment.
Overall conversion efficiency is very poor.
Sources are located at remote places with
reference to load, increasing transmission cost.
Maintenance cost is high.
Transmission
Transmission System
Lines/transformers operating at voltages above115 kV are usually called the transmission system.
Consists of Transmission Line and Sub-stations
Transmission Line◦ Overhead Lines
◦ Cable Underground Cables
Submarine Cables
Sub-stations
Transmission Towers
Insulators
Overhead Line Conductors•Aluminum conductor steel-reinforced
cable (ACSR cable) is a specific type of
high-capacity, high-strength stranded
cable typically used in overhead power
lines.
•The outer strands are aluminum,
chosen for its excellent conductivity,
low weight and low cost. The center
strand is of steel for the strength
required to support the weight without
stretching the aluminum due to its
ductility. This gives the cable an overall
high tensile strength.
Substations
Size of substation
◦ Depends on transformer size
Types of Sub-station
◦ Conventional outdoor
Require bigger space
◦ GIS (gas insulated switchgear)
Less space
Outdoor or indoor
Sub-station Components
Transformer
Circuit Breaker / Switch Gear
Isolator Switches
Busbar
Protection Relay & Control Equipment
Power Transformer
Sub-station Components
Circuit Breaker / Switch Gear
Busbar
Distribution
Lines/transformers operating at voltages below
115 kV are usually called the distribution
system.
Part of the electric utility system between the
bulk power source and the customer service
entrances (loads).
33kV, 22kV, 11kV, 6.6kV, 415V and 240V
Distribution System
Distribution Intakes (33kV, 22kV)
Distribution Substations (22kV, 11kV, 6.6kV)
◦ Indoor substation
◦ Outdoor substation
◦ Pole mounted substation
◦ Compact substation
◦ Underground substation
Transformer capacity
◦ 100kVA, 300kVA, 500kVA, 750kVA and 1000kVA
Distribution Substations
Distribution Intake
Distribution Substations
Indoor Sub-station
Distribution Substations
Underground Sub-station
Distribution Substations
Compact Sub-station
Distribution Substations
Outdoor Sub-station
Distribution Substations
Pole-Mounted Sub-station
Distribution Substations
Types of Load:
◦ Residential
◦ Commercial
◦ Industrial
◦ Public Transportation
◦ Public Lighting
◦ etc.
Power System Loads
Residential Load
Consist of lighting, radio, TV, refrigerator, kitchenappliances, washing machine and etc.
Usually, increases in the evening around 6 p.m. and returnto a nominal value around 12 p.m.
Commercial Load
• Consists of lighting, air-condition and small appliances.
• Shops, business premises, schools, universities etc.
• The load is fairly constant from 9am until 9pm with the
exception of any mid-day break.
Power System Loads
Industrial Load
Mainly consists of motor load, air conditioner, lighting, welding and furnaces etc.
It can be divided into small, medium and large category.
The nature of industrial load curve depends on the number of shifts worked in the industry.
Power System Loads
Power System Loads
Electricity energy cannot be stored.
Generate electricity based on demand.
Total power drawn by consumer fluctuates
depends on the time of day and seasons.
Demand Curve
◦ Plot each demand of electricity by consumer
daily/annually
Demand Curve