Question

State the meaning of FACTS and explain in brief d-types facts controller.

Answer 1

### FACTS (Flexible AC Transmission Systems)
FACTS stands for Flexible AC Transmission Systems. It refers to a collection of technology used in power systems to enhance the controllability and stability of electrical power transmission networks. FACTS devices are used to control various parameters like voltage, power flow, and impedance in an AC transmission system. The main goal is to improve the efficiency and reliability of power transmission while reducing transmission losses and maintaining system stability.

D-Types FACTS Controllers

D-type FACTS controllers refer to a category of FACTS devices that are designed to control the dynamic response of a power system. These controllers primarily manage the active and reactive power flow to achieve optimal operation of the power network.

Here are some common D-type FACTS controllers:

1. SVC (Static Var Compensator):
   

   - Controls reactive power and helps in voltage regulation.
   - It uses a combination of capacitors and inductors with thyristor-controlled elements to adjust the amount of reactive power supplied or absorbed from the system.

1. STATCOM (Static Synchronous Compensator):
   

   - Similar to the SVC, but it uses voltage-sourced converters (VSC) instead of thyristor-controlled elements.
   - Provides dynamic reactive power support and better performance, especially in systems with rapidly changing conditions.

1. UPFC (Unified Power Flow Controller):
   

   - One of the most advanced FACTS controllers, capable of controlling both active and reactive power in the system.
   - It combines a series compensator and a shunt compensator, providing flexibility to control the voltage, power flow, and impedance in the transmission line.

In short, D-type controllers like SVC, STATCOM, and UPFC are used to maintain system stability, improve voltage regulation, and optimize the power flow in transmission lines to prevent power outages and improve efficiency. They do this by dynamically controlling the flow of reactive power and helping stabilize voltage levels.