EMERGING FACTS CONTROLLERS
1. What is meant by emerging facts controllers?
The emerging facts controllers exchange the reactive power to the transmission lines with the help of phase shifting techniques. If needed the real power is also supplied in addition to the reactive power in to the transmission line with the help of emerging FACTS devices such as STATCOM and UPFC. Here the need of large size capacitor bank and inductor bank are reduced, so the operating performance will be improved.
2. What is meant by STATCOM?
The static synchronous compensator (STATCOM or SSC) is a shunt connected reactive power compensation device that is capable of generating and/or absorbing reactive power and in which the output can be varied to control the specific parameters of an electric power system. It is capable of generating or absorbing independently controllable real and reactive power at its output terminals when it is fed from an dc energy source or energy storage device at its input terminals.
3 . What are the functions of STATCOM in the improvement of power system performance area?
It provides dynamic voltage control in transmission and distribution system
It provides damping against the oscillation in power system.
It provides better transient stability
It has voltage flicker control (it withstands sudden changes)
It controls both real and reactive power
4. What are the common advantages of STATCOM?
It required small space because it replaces the passive inductor and capacitor bank by compact electronic converters.
It has modular factory build electronic equipments, so site work and commissioning time will be reduced.
It uses encapsulated electronic converters, thereby minimizing its environmental impact.
5. Give details about first installed STATCOM
device at Sullivan Sub-station.
Tennessee Valley Authority (TVA) installed the first ± 100 MVA STATCOM in 1995 at its Sullivan substation.
6. What are the applications of first installed STATCOM device at Sullivan Sub-station?
The application of this STATCOM is expected to reduce the TVA’s need for load tap changing transformers, there by achieving savings by minimizing the potential for transformer failure. This STATCOM solves the problems against off-peak dilemma of over voltages in the Sullivan substation area while avoiding the more labor and apace intensive installation of an additional transformer bank.
7. What are the advantages of first installed STATCOM device at Sullivan Sub-station?
It increases the capacity of transmission line voltage by providing instantaneous control.
It provides greater flexibility in bulk power transactions.
It also increases the system reliability by damping grids of major oscillations in this grid.
8. Write short notes on principle of operation of STATCOM.
A STATCOM is a controlled reactive power source. It provides the desired reactive power generation and absorption entirely by means of electronic processing of the voltage and current waveforms in a voltage source converter.
9. Give the explanation about reactive power exchange between converter and the ac system.
If the ac system voltage is lesser than the sending end voltage then the converter inject the reactive power to the transmission line. If the ac system voltage is higher than the sending end voltage then the converter absorb the reactive power from the transmission line.
10. What is the importance of V-I characteristics of STATCOM?
The V-I characteristics of STATCOM shows that it can supply both the capacitive and inductive compensation and is able to independently control its output current over the rated maximum capacitive or inductive range irrespective of the amount of ac system voltage. That is, the STATCOM can provide full capacitive reactive power at any ac system voltage even as low as 0.15 p.u.