REACTIVE POWER CONTROL
Ø “To make transmission networks operate within desired voltage limits and methods of making up or taking away reactive power is called reactive-power control”.
Ø The AC networks and the devices connected to them create associated time-varying electrical fields related to the applied voltage and as well as magnetic fields dependent on the current flow and they build up these fields store energy that is released when they collapse”.
Ø Apart from the energy dissipation in resistive components, all energy-coupling devices (e.g: motors and generators) operate based on their capacity to store and release energy.
Ø While the major means of control of reactive power and voltage is via the excitation systems of synchronous generators and devices may be deployed in a transmission network to maintain a good voltage profile in the system.
Ø The shunt connected devices like shunt capacitors or inductors or synchronous inductors may be fixed or switched (using circuit breaker).
Ø The Vernier or smooth control of reactive power is also possible by varying effective susceptance characteristics by use of power electronic devices. Example: Static Var Componsator(SVC)” and a Thyristor Controlled Reactor (TCR).