Reactive Power Stabilize Voltage

The voltage along transmission line depends upon

• Capacitive charging current and 
• Loading of the Line

Capacitive charging current

• The capacitance charging current depends upon capacitance between line and earth and its value depends upon geometry of the line. 
• The capacitance generates reactive power and it is expressed in MVAr ( Here small ‘ r ‘ stands for reactive power )

Loading of the line

• The load and line itself consumes reactive power.

Reactive Power Generation in the Transmission Line	Reactive Power Absorb in the Transmission Line
Capacitance between transmission line and Ground	Transmission line itself and load

Balance of Reactive power

• It is necessary to balance generation and absorb of reactive power. 
• The reactive power determines the voltage stability of the line whether it is overload lines or cable. 
• If there is large amount of reactive power generation than absorb, the voltage will increase. 
• If there is lack of reactive power, the voltage will decrease.  Therefore the reactive power must be controlled for voltage stability.

Effect of Reactive Power	Effect
Reactive Power Generation > Reactive Power Absorb	Voltage Increases
Reactive Power Generation < Reactive Power Absorb	Voltage Decreases
Reactive Power Generation = Reactive Power Absorb	Voltage Stabilize

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