Power Quality By Using FACTS

CONTENTS INTRODUCTION WHAT IS FACTS? FOR WHAT PURPOSE FACTS ARE USED? BASIC TYPES OF FACTS CONTROLLERS BENEFITS OF UTILISING FACTS DEVICES APPLICATION OF FACTS CONTROLLERS CONCLUSION

INTRODUCTION N.G. Hingorani, in 1988,first defined the concepts of Flexible AC Transmission Systems(FACTS). The Reactive Power has been recognized as significant factor in the design and operation of ac systems for a long time. In an Ideal AC Power system,the voltage and frequency at every supply point would be constant and free from harmonics and Power factor would be unity irrespective of consumers load. In case of Non ideal AC Power system which is due to varying loads, the terminal voltage tends to be varying and it requires the generation of reactive power as close as possible to load

WHAT IS FACTS? FACTS Technology is a collection of power electronics controllers which can be applied individually or in coordination with others to control system parameters such as voltage,current,series impedance shunt impedance etc.., that govern the operation of transmission systems. FACTS involve conversion and/or switching power electronics in the range of few tens of a few hundred mega watts. FACTS-a new technology based on power electronics offering an opportunity to enhance the controllability, stability and power transfer capability of transmission system.

FOR WHAT PURPOSE FACTS ARE USED? FACTS devices are used for dynamic control of voltage, impedance and phase angle of high voltage ac lines. FACTS controllers enable the routing the power in steady state. FACTS devices has other potential advantages : 1. Ability to damp oscillations 2. Improve system stability 3. It enhances power transfer capacity of transmission network.

BASIC TYPES OF FACTS CONTROLLERS Series controllers. Shunt controllers. Combined series-series controllers. Combined shunt-series controllers.

SERIES CONTROLLERS Series controllers could be variable impedance, such as capacitor, reactor, etc power electronics based variable source of main frequency,sub synchronous and harmonic frequencies to serve the desired need. In principle,all series controllers inject voltage in series with the line. As long as the voltage is in phase quadrature with the line current,the series controller only supplies or consumes the reactive power. Any other phase relationship will involve handling of real power as well.

TYPES OF SERIES COMPENSATION

SHUNT CONTROLLERS In principle,all shunt controllers inject current into the system at the point of connection. As long as the injected current is in phase quadrature with the line voltage, the shunt controller only supplies or consumes variable reactive power. Types of shunt controllers  SVC-Static Var Compensator.  STATCOM-Static compensator.

SVC-Static Var Compensator

STATCOM-Static compensator

UPFC CONFIGURATION

BENEFITS OF UTILISING FACTS DEVICES Control of power flow in transmission by controlling line impedance, angle and voltage. Optimum power flow. Increase in loading capability of lines to their thermal capabilities. Increase in system security through raising the transient limit, limiting short circuit currents and over loads. Provides greater flexibility. Upgrade of lines. Reduce loop flows.

APPLICATIONS OF FACTS CONTROLLERS Power flow control. Voltage control. Reactive power compensation. Stability improvement. Interconnection of renewable and distributed generation storages. Power conducting. Power quality improvement. Increase of transmission capability.

CONCLUSION FACTS technology is a collection of power electronics controllers which can be applied individually or in coordination with others to control one or more system parameters such as voltage current power etc. The advent of high power self commutating device,high speed computing elements and advanced control concepts have made flexible control of as network a practical reality.