1. Power System Structure
EE Elective 1 – Power Systems Planning
By John Larry Corpuz & Patrick Alcantara
BS Electrical Engineering
PERPETUAL HELP
UNIVERSITY OF
SYSTEM DALTA
2. Boylestad, R. L., & Nashelsky, L. (2014). Electronic Devices and circuit theory. Pearson Education.
An electrical power system consists
of
• Generation
• Transmission
• Distribution
3. An electrical power system consists of
• Generation
• Transmission
• Distribution
• Generation
• It is where the energy is converted from
one form of energy into electrical energy
• Some of which are the thermal power
plants which converts heat energy into
mechanical energy, then into electrical
energy
• Generating voltages are usually 6.6 kV,
10.5 kV, 11 kV, 13.8 kV, 15.75 kV, etc.
4. An electrical power system consists of
• Generation
• Transmission
• Distribution
• Distribution
• Transmission systems supply bulk power and the
systems transfer electric power to ultimate consumers
• Efficient long-distance transmission of electric power
requires high voltages. This reduces the losses produced by
heavy current.
• Transmission lines mostly use high-voltage AC (alternating
current), but an important class of transmission line uses high
voltage direct current.
• The voltage level is changed with transformers, stepping
the voltage for transmission, then reducing voltage for local
distribution and then use by customers.
5. An electrical power system consists of
• Generation
• Transmission
• Distribution
• Distribution
• Electric power distribution is the final stage in the
delivery of electric power; it carries electricity from
the transmission system to individual consumers.
• Distribution substations connect to the
system and lower the transmission voltage to
medium voltage with the use of transformers.
• The transition from transmission to distribution
happens in a power substation, which has the
following functions:
• Circuit breakers and switches enable the substation to be
disconnected from the transmission grid or for distribution lines
to be disconnected.
• Transformers step down transmission voltages, 35 kV or more,
down to primary distribution voltages. These are medium voltage
circuits, usually 600–35000 V.
• From the transformer, power goes to the busbar that can split the
distribution power off in multiple directions. The bus distributes
power to distribution lines, which fan out to customers.
6. Components of a power system
• Generators
• A device used to convert one form of
energy into electrical energy
• Transformer
• Transfers power or energy from one circuit
to other without the change of frequency
• Transmission lines
• Transfer power from one location to
another
• Control Equipment
• Used for protection purposes
7. Components of a power
system
• Primary Transmission
• 110kV, 132kV, or 220kV or
higher V. 3φ-3 wire
• Secondary Transmission
• 33kV or 66kV. 3φ-3 wire
• Primary Distribution
• 3φ-3 wire, 11kV or 6.6kV
• Secondary Distribution
• 400V for 3φ, 230V for 1φ
8. Generators
• Generator is a device which
converts mechanical into
electrical energy
• Generating voltages are typically
6.6, 10.5, or 11 kV
• Can step up to 110/132//220 kV
to reduce current in
transmission, therefore losses
• Produces Real Power (MV) and
Reactive Power (MVAR)
9. Transformers
• Static device which transfers
power or energy from one circuit
to another without frequency
change
• Step-up voltage from lower
generation to higher generation
voltage
• Step down voltage from higher
transmission voltage for
distribution
• High voltage reduce transmission
loss in the grid
10. Control Equipment
• Circuit Breaker: used for opening
or closing a circuit at normal and
fault
• Oil circuit breaker, air-blast,
vacuum, etc.
• During fault conditions, relay will
give command to breaker to
operate
• Isolators: placed in substation to
isolate the part of the system
• Operates only during no-load
condition.
11. Busbar
• They are used to connect number
of lines operating at same voltage
• It is made up of copper or
aluminum
• Arrangement types are:
• Single busbar
• Single busbar with sectionalisation
• Double busbar arrangements
• Ring busbar scheme
12. Transmission System
• Supplies only large blocks of
power to bulk power station or
very big consumers
• Connects neighboring generating
stations in to a power pool
• Interconnection of two or more
generating stations
• Tolerance of +/- 5 to 10% due to
load variations
