Diagram and Operation of Phase Angle Regulator Which Compensates Reactive Power

I'm not sure where you are looking to achieve power factor correction. The closest I'll guess is that you need a brushed synchronous motor used as a synchronous condenser.

there are 3 conventional reactive power compensators.

as u told the first one is synch condensor.

the other 2 are saturable reactors and phase angle reactor(PAR).

i need to know the diagram and working of PAR

http://en.wikipedia.org/wiki/Static_VAR_compensator

You're in luck.
You should search some more. The answer is before you.

See:

http://en.wikipedia.org/wiki/Quadrature_booster

Karthiga,

I assume that this was an interview question. It is designed to test your knowledge of how power flows in a grid can be controlled, something only an experienced power engineer (or a really, really diligent student) would know.

Think of it this way, there are two components to Apparent Power (S), Real Power (W) and Reactive Power (VAR); therefore, there are only two control actions that can be taken to affect these two quantities. We can change the phase angle between two points which changes the real power flow, or we can change the voltage which changes the reactive power flow, or any combination of both. Two variables, four degrees of freedom, four quadrants of operation.

At a generating station changing the fuel supply affects the phase/torque/power angle, while changing the rotor current affects the voltage level. On the grid the PAR and reactive elements such as LTC (Load Tap Changer), synchronous condensers, capacitors, etc. perform the equivalent functions.

7anoter4,

From your Wiki article: "...A phase angle regulating transformer, phase angle regulator (PAR, American usage), phase-shifting transformer, or quadrature booster (quad booster, British usage), is a specialised form of transformer used to control the flow of real power..."

Real power, not reactive power; there is no such thing as a PAR significantly affecting VAR flow, only reactive elements such as LTC (Load Tap Changer), synchronous condensers, capacitors, etc. do that.

Class dismissed,

Alan