Introduction
Power flow studies are great of importance in many
applications of power system such as planning and designing the future
expansion of power systems as well as in determining the best operation of
existing system.
The principle information obtained from power flow
study is
the magnitude and phase angle of the voltage at each bus and the real
and reactive power flowing in each line. However, much additional information
of value is provided by the print out of the solution from computer programs
used by the electric utility companies.
The following table shows summery of some important
practical applications of load flow studies and corresponding description:
Application
|
Description
|
Transmission planning
|
Use load
flow to check for overloads ,voltage problems, and to identify location of
network reinforce-ments
|
Contingency analysis
|
Teat for
effect line and/or generator outages
|
VAR/ Voltage analysis
|
Evaluate
effectiveness of VAR/voltage devices
|
Transfer capability analysis
|
Test for
inter-utility power transfer limits.
|
On line control, security
analysis
|
Analyze
effectiveness of corrective measures to alleviate emergencies
|
Table (1-1) Practical
application of load flow studies
Importance Of Power Flow Study
The importance of power flow study can be summarized
as following:
The total generation power in the network supplied from the generator
station must equal the demand plus the network losses at each moment , the
individual generator outputs must be closely maintained at predetermined set
points. It is remember that the demand undergoes slow but wide changes
throughout the whole day. This means that a load flow configuration that fits
the demand of a certain hour of the day may look quite different the next hour.
Transmission links can carry only power less than their stability or
thermal limits (security constraints to avoid any over loads ).
The voltage level of the system buses are necessary to keep within certain tolerance (upper & lower limits ) .
The power system must fulfill certain contractual power –scheduling commitment via its tielines to neighboring systems.
The effects of system outage (generation units or transformers or lines) can be minimized by proper prefault power flow strategies.
Power flow analysis are very important in thy planning stages of new networks or extension to existing ones.
The voltage level of the system buses are necessary to keep within certain tolerance (upper & lower limits ) .
The power system must fulfill certain contractual power –scheduling commitment via its tielines to neighboring systems.
The effects of system outage (generation units or transformers or lines) can be minimized by proper prefault power flow strategies.
Power flow analysis are very important in thy planning stages of new networks or extension to existing ones.
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