Environmental Engineering Reference
In-Depth Information
400 kV
400 kV
Generation
plant
Generation
plant
G
G
Step-up
transformer
Transmission
system
400 kV
400 kV
Bulk power
substation
Sub-transmission
system
275 kV
275 kV
Step-down
transformer
132 kV
132 kV
Large and small
industrial
customers
Distribution
substation
Distribution
system
11 kV
Primary
distribution
Service
transformers
DG
230/400 V
Secondary
Distributed
generation
Commercial
customers
Residential
customers
Figure 3.1
Overview of the electrical transmission and distribution infrastructure
[177]
follows a set of physical laws in order to move electricity from one point to another.
As depicted in Figure 3.1, the main concept of a power delivery system consists
of hierarchical voltage levels. Therefore, power can be thought of as moving down
through various levels while simultaneously reducing the operating voltage at which
it flows.
Electrical delivery systems consist of several key power delivery stages which
are usually classified as:
Transmission system : Functions as the interconnected grid infrastructure between
major power producing plants and main load centres; by operating at high-voltage
levels these intricate lines provide a strong bond between generators and the
sub-transmission system, so they can stay synchronised.
Sub-transmission system : Fulfils the purpose of taking power from transmission
substations and delivers it to the distribution substations; usually at this stage
large industrial customers and other energy intensive users are supplied.
Distribution substations : Function as the centres that link the transmission grid
with the distribution primary feeder system. This key task is achieved through
transformers that convert the incoming power from sub-transmission voltage
 
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