seminar code
04-08-2014, 02:41 PM
Power Upgrading of Transmission Line by Injecting DC Power in to AC
Line with the help of ZIG-ZAG Transformer.
[attachment=66566]
Abstract
We never loaded a long extra high voltage to
their thermal limits in order to keep sufficient margin
against transient instability. With this scheme proposed in
this paper, it is possible to load these lines very near to their
thermal limits. Here we inject dc power in to dc transmission
line to carry usual ac along with dc superimposed on it. The
added power flow does not cause any transient instability.
This paper presents the feasibility of converting a double
circuit ac line into composite ac–dc power transmission line
to get the advantages of parallel ac–dc transmission to
improve stability and damping out oscillations. Simulation
and experimental studies are carried out for the coordinated
control as well as independent control of ac and dc power
transmissions. No alterations of conductors, insulator
strings, and towers of the original line are needed.
Substantial gain in the loadability of the line is obtained.
Master current controller senses ac current and regulates
the dc current orders for converters online such that
conductor current never exceeds its thermal limit.
INTRODUCTION
The feasibility study of conversion of a double circuit ac
line to composite ac–dc line without altering the original line
conductors, tower structures, and insulator strings has been
presented. In this scheme, the dc power flow is point-to- point
bipolar transmission system. Clerici et al. [7] suggested the
conversion of ac line to dc line for substantial power upgrading
of existing ac line. However, this would require major changes
in the tower structure as well as replacement of ac insulator
strings with high creepage dc insulators. The novelty of our
proposed scheme is that the power transfer enhancement is
achieved without any alteration in the existing EHV ac line. The
main object is to gain the advantage of parallel ac–dc
transmission and to load the line close to its thermal limit.
In recent years, environmental, right-of-way, and cost
concerns have delayed the construction of a new transmission
line, while demand of electric power has shown steady but
geographically uneven growth. The power is often available at
SIMULTANEOUS AC–DC POWER TRANSMISSION
Fig. 1 depicts the basic scheme for simultaneous ac–dc
power flow through a double circuit ac transmission line. The dc
power is obtained through line commutated 12-pulse Rectifier
Bridge used in conventional HVDC and injected to the neutral
point of the zigzag connected secondary of sending end
CONCLUSION
The feasibility to convert ac transmission line to a
composite ac–dc line has been demonstrated. For the particular
system studied, there is substantial increase (about 83.45%) in
the loadabilty of the line. The line is loaded to its thermal limit
with the superimposed dc current. The dc power flow does not
impose any stability problem. The advantage of parallel ac–dc
transmission is obtained. Dc current regulator may modulate ac
power flow. There is no need for any modification in the size of
conductors, insulator strings, and towers structure of the original
line. The optimum values of ac and dc voltage components of
the converted composite line are 1/2 and times the ac voltage
before conversion, respectively
Line with the help of ZIG-ZAG Transformer.
[attachment=66566]
Abstract
We never loaded a long extra high voltage to
their thermal limits in order to keep sufficient margin
against transient instability. With this scheme proposed in
this paper, it is possible to load these lines very near to their
thermal limits. Here we inject dc power in to dc transmission
line to carry usual ac along with dc superimposed on it. The
added power flow does not cause any transient instability.
This paper presents the feasibility of converting a double
circuit ac line into composite ac–dc power transmission line
to get the advantages of parallel ac–dc transmission to
improve stability and damping out oscillations. Simulation
and experimental studies are carried out for the coordinated
control as well as independent control of ac and dc power
transmissions. No alterations of conductors, insulator
strings, and towers of the original line are needed.
Substantial gain in the loadability of the line is obtained.
Master current controller senses ac current and regulates
the dc current orders for converters online such that
conductor current never exceeds its thermal limit.
INTRODUCTION
The feasibility study of conversion of a double circuit ac
line to composite ac–dc line without altering the original line
conductors, tower structures, and insulator strings has been
presented. In this scheme, the dc power flow is point-to- point
bipolar transmission system. Clerici et al. [7] suggested the
conversion of ac line to dc line for substantial power upgrading
of existing ac line. However, this would require major changes
in the tower structure as well as replacement of ac insulator
strings with high creepage dc insulators. The novelty of our
proposed scheme is that the power transfer enhancement is
achieved without any alteration in the existing EHV ac line. The
main object is to gain the advantage of parallel ac–dc
transmission and to load the line close to its thermal limit.
In recent years, environmental, right-of-way, and cost
concerns have delayed the construction of a new transmission
line, while demand of electric power has shown steady but
geographically uneven growth. The power is often available at
SIMULTANEOUS AC–DC POWER TRANSMISSION
Fig. 1 depicts the basic scheme for simultaneous ac–dc
power flow through a double circuit ac transmission line. The dc
power is obtained through line commutated 12-pulse Rectifier
Bridge used in conventional HVDC and injected to the neutral
point of the zigzag connected secondary of sending end
CONCLUSION
The feasibility to convert ac transmission line to a
composite ac–dc line has been demonstrated. For the particular
system studied, there is substantial increase (about 83.45%) in
the loadabilty of the line. The line is loaded to its thermal limit
with the superimposed dc current. The dc power flow does not
impose any stability problem. The advantage of parallel ac–dc
transmission is obtained. Dc current regulator may modulate ac
power flow. There is no need for any modification in the size of
conductors, insulator strings, and towers structure of the original
line. The optimum values of ac and dc voltage components of
the converted composite line are 1/2 and times the ac voltage
before conversion, respectively