Improvement of power system stability
with by SSSC-based cascade control
Journal Name:
- Dicle Üniversitesi Mühendislik Fakültesi Mühendislik Dergisi
Keywords (Original Language):
| Author Name | University of Author |
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Abstract (2. Language):
In control systems, when a destructive comes to the
system, it is necessary for the system to show a good
performance towards that destructive. Being an
alternative to conventional control system, Cascade
Control increases the performance of the control
system especially when there is an unpredictable
destructive. In this study, the control of the system is
ensured with Cascade Control structure over single
machined power system connected to infinite bus bar
including SSSC (Static Synchronous Series
Compensator). SSSC is a FACTS (Flexible AC
transmission systems) controller that is connected in
series to the power system. FACTS controllers can
be used in controlling power flow and improving
temporary and permanent stability of the systems.
Also, oscillation generated in the power system can
be reduced. These FACTS controllers reduce
reactive power flow and consequently provide more
active power flow through transmission line. By
injecting voltage in an appropriate phase angle for
power system, SSSC changes the effective impedance
of the transmission line. SSSC is preferable in
providing the active and reactive power control in
the power system. Reactive power control is
performed depending on the voltage amplitude value
of the system. Active power control is performed
depending on the angle amplitude value. In Cascade
Control structure, conventional PID controllers are
used for internal and external loop. In the cascade
control structure proposed by this study, PI
controller is used for the internal loop, and PID is
used for the external loop. The controller
parameters of the internal and external loop in
cascade control structure were obtained by genetic
algorithm (GA) method. GA are based on natural
selection and natural inheritance rules in real life.
Natural selection means the survival of organisms
that have adapted to the environmental conditions,
and the elimination of which is not fit, that means
dying. The natural inheritance may be summarized
as mating with each of the individuals selected to
form new offspring. The performance of the
proposed cascade controller have been compared
with SSSC for damping controller and conventional
PID controller performance in the literature.
Conventional PID control system and PID
controllers are used in the most of automatic
feedback control device in the industry.
PID (proportional + integral + differential) control
agents in the second degree offers the optimum
solution for linear time-delay-free system. SSSC for
damping controller also provides power system
oscillation damping. Speed deviation is used as the
input signal of the SSSC for damping control, while
the damping control signal provided by the
controller is used as output signal. Other controller
parameters are those of the lead-lag structures
located in the control system issues. After the
evaluation of the results obtained in this
comparison, the proposed cascade controller in
normal load situation showed 19% better
performance compared to the SSSC for damping
controller, and it showed 14% better performance
compared to the conventional PID controller. Under
heavy load condition, the proposed cascade
controller showed 21% better performance than the
SSSC for damping controller, and 14% better
performance than the conventional PID controllers.
In the case of light load conditions, the proposed
cascade controller showed 10% better performance
than SSSC for damping controller, and 7% better
performance than the conventional PID controller.
In addition, the proposed cascade controller has
been observed to have a less speed deviation than
the SSSC for damping controller and the
conventional PID controllers under normal, light,
and heavy load conditions. Also, it has been
observed that the proposed cascade has stability and
it settled in a short time.
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Abstract (Original Language):
Kontrol sistemlerinde sisteme herhangi bir bozucu geldiğinde bu sistemin bozucu karşısında iyi bir
performans göstermesi gerekir. Klasik kontrol sisteminin bir alternatifi olan Kaskad Kontrol
yöntemi, özellikle öngörülmeyen bozucuların varlığında kontrol siteminin performansını
artırmaktadır. Bu çalışmamızda, Statik Senkron Seri Kompansatör (SSSC) içeren sonsuz baraya
bağlı tek makineli güç sisteminde kaskad kontrolör yapısı kullanılarak sistemin karalılığının
iyileştirilmesi sağlanmıştır. Kaskad kontrol yapısında iç ve dış döngüde klasik PID (Oransal +
İntegral + Türevsel) tip kontrolörler kullanılmaktadır. Bu çalışmadaki kaskad kontrol yapının iç
döngüsünde PI, dış döngüsünde ise PID kontrolörler kullanılmıştır. Kaskad kontrol yapısının iç ve
dış döngüsünde bulunan kontrolörlerin ayar parametre değerleri Genetik Algoritma (GA) yöntemi
kullanılarak elde edilmiştir. Önerilen kaskad kontrolörün performansı, literatürde bulunan sonsuz
baraya bağlı tek makineli güç sisteminin SSSC için sönümleme kontrolörü ve klasik PID kontrolörü
performansları ile karşılaştırılmıştır. Bu karşılaştırmalar neticesinde elde edilen sonuçların
değerlendirilmesi sonucunda normal yük durumunda önerilen kaskad kontrolörün, SSSC için
sönümleme kontrolörüne göre %19, klasik PID kontrolörüne göre de %14 daha iyi performans
göstermiştir. Ağır yük durumunda, önerilen kaskad kontrolörün, SSSC için sönümleme kontrolörüne
göre %21, klasik PID kontrolörüne göre de %14 daha iyi performans göstermiştir. Hafif yük
durumu şartlarında ise önerilen kaskad kontrolörün, SSSC için sönümleme kontrolörüne göre %10,
klasik PID kontrolörüne göre de %7 daha iyi performans göstermiştir.
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