Applications of Flexible AC Transmission System (FACTS)


FACTS(Flexible AC Transmission System) as narrated by IEEE is the AC power transmission system with power electronics-based devices attached to control power flows to operate the power system within the stable limits. FACTS devices are used to enhance the reliability and control ability of old power transmission systems. This technology is growing at a very fast pace and continuous research is ongoing in this domain. The huge involvement of distributed generation within the distribution network is prone to different power systems stability issues like voltage dips, unbalanced reactive power compensation, and harmonics, etc. Nowadays, FACTS devices are employed to mitigate these problems by providing full control ability and reliability.

 One or more of the following steady-state and dynamic restrictions hinder the transmission system’s ability to deliver power:

  1. Angular stability
  2. Voltage magnitude
  3. Thermal limits
  4. Transient stability
  5. Dynamic stability

The maximum electrical power that can be transmitted without causing harm to transmission lines and electrical equipment is defined by these restrictions. The expansion of generation and transmission line facilities can always alleviate the limits on power transfer.

Improved Reliability and Power Control ability

The reactive power flow in the power system plays an important role in the power system stability. The old transmission system did not qualify to control reactive power flow within the transmission lines. Deployment of FACTS controllers in the power transmission system is the solution to get full control ability of reactive power flow in the power transmission system.

The advent of power electronics-based devices in the field of power systems played a huge role in the development of various power condensers. Some of the most important power electronics devices that are the heart of FACTS are Thyristors, IGBT’s and GTO. These are extensively used in the fabrication of most of the FACTS controllers that are used to absorb or supply reactive power to the system.

There are three types of FACTS Controllers:

  1. Series Controller which is connected in series with the line and its main task is to supply voltage in the line.
  2. Shunt Controller is connected parallel with the line and its main task is to supply current in the line.
  3. Combined Series Shunt Controller supply voltage in the line by series part and current in the line by shunt part.
Facts Controllers

Author: Ali Hassan | Event Management and Logistics

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