30-04-2012, 01:36 PM
Flexible AC Transmission Systems (FACTS) Controllers
Dr. NVS FACTS ppt.ppt (Size: 530.5 KB / Downloads: 63)
The power system is an interconnection of generating units to load centers through high voltage electric transmission lines and in general is mechanically controlled.
It can be divided into three sub-systems: generation, transmission and distribution. Until recently all these three sub-systems were under supervision of one body within a certain geographical area providing power at regulated rates.
In order to provide cheaper electricity the deregulation of power system, which includes separate generation, transmission and distribution companies, is already being implemented.
At the same time electric power demand continues to grow and also building of the new generating units and transmission circuits is becoming more difficult because of economic and environmental reasons.
Therefore, power utilities are forced to relay on utilization of existing generating units and, to load existing transmission lines closer to their thermal limits.
Types of FACTS Controllers
FACTS controllers can be broadly divided into four categories, which are
Series controllers.
Shunt controllers.
Combined series-series controllers.
Combined series-shunt controllers.
Series Controllers
Series controllers shown are essentially are of two type’s viz. variable impedance type and converter type.
Variable impedance type may be regarded as variable reactive or capacitive impedance connected in series with the line and whose value is adjusted to damp out low frequency oscillations like sub-synchronous resonance etc. that can take place in the system.
Converter type is a voltage source converter, which is connected in series with the line through a boosting transformer.
Conventional Transmission and Control Capability
Viewing the operation of the unified power flow controller from the stand point of traditional power transmission based on reactive shunt compensation, series compensation, and phase shifting.
The UPFC can fulfill all these functions and thereby meet multiple control objectives by adding the injected voltages VPQ, with appropriate amplitude and phase angle, to the (sending end) terminal voltage VS.
Dr. NVS FACTS ppt.ppt (Size: 530.5 KB / Downloads: 63)
The power system is an interconnection of generating units to load centers through high voltage electric transmission lines and in general is mechanically controlled.
It can be divided into three sub-systems: generation, transmission and distribution. Until recently all these three sub-systems were under supervision of one body within a certain geographical area providing power at regulated rates.
In order to provide cheaper electricity the deregulation of power system, which includes separate generation, transmission and distribution companies, is already being implemented.
At the same time electric power demand continues to grow and also building of the new generating units and transmission circuits is becoming more difficult because of economic and environmental reasons.
Therefore, power utilities are forced to relay on utilization of existing generating units and, to load existing transmission lines closer to their thermal limits.
Types of FACTS Controllers
FACTS controllers can be broadly divided into four categories, which are
Series controllers.
Shunt controllers.
Combined series-series controllers.
Combined series-shunt controllers.
Series Controllers
Series controllers shown are essentially are of two type’s viz. variable impedance type and converter type.
Variable impedance type may be regarded as variable reactive or capacitive impedance connected in series with the line and whose value is adjusted to damp out low frequency oscillations like sub-synchronous resonance etc. that can take place in the system.
Converter type is a voltage source converter, which is connected in series with the line through a boosting transformer.
Conventional Transmission and Control Capability
Viewing the operation of the unified power flow controller from the stand point of traditional power transmission based on reactive shunt compensation, series compensation, and phase shifting.
The UPFC can fulfill all these functions and thereby meet multiple control objectives by adding the injected voltages VPQ, with appropriate amplitude and phase angle, to the (sending end) terminal voltage VS.