Every generator has got its own load angle. Some generators are connected to the same bus. Each bus has got a voltage & a load angle. If 5 generators are connected to a single bus & each generator has its own load angle, then how is the load angle of that bus determined? (....& yes i know that the angle of bus is also called "power angle")

 

In simple terms, a generator can be represented by an internal emf source connected through an inductance to the terminal voltage. If you do the maths on this configuration, the real or active power delivered to the terminals is given by the expression (Eint x Vterm)/X x sin (alpha) where alpha is the phase angle difference between the two voltages. So the term load angle applies to the difference between the internal emfs of each generator and the external common bus. In that context, the "load angle of the bus" is meaningless - the phase of the bus voltage is the reference used to express the individual phase angles of each machine.

But to get the power out of the bus and away from the generating station, there is a phase difference between the local bus and the "infinite bus" of the connected system as a whole - but that's another whole can of worms.

Bruce

 

Siddharth… buses having generators connected to them are referred to as generator buses; all others, even without "electrical-loads" are called load-buses. The angle term you ascribed to a load-bus, i.e., "power-angle" is non-existent! Instead a bus has a voltage magnitude and a corresponding "voltage-angle" often referred to some other another bus.

For example, imagine two buses: one, labeled Bus1; the other Bus2. Bus1 has a generator supplying an "electrical load", P1+jQ1, so that Bus1 voltage is V1 at angle Theta1.

Now imagine Bus1 connected to Bus2 through an Impedance, Z12. Another "electrical load", P2+jQ2 is connected to Bus2. Then, current flowing through Z12, and if Bus1 is the reference bus (Theta1 = 0 deg), Bus2 voltage is V2 at angle Theta2. That angle is referred to as the "Voltage-Angle!"

BTW, Bus1 can also be referred to as the "Swing-Bus" and Bus2's Theta2 angle, while related to Bus2's "electrical-load" is not called the "load-angle!"

If you would like an example with numbers, as well as the procedure for determining V1 @ Theta1 and V2 @ Theta 2, let me know.

Regards, Phil Corso