In load flow studies PV bus is treated as PQ bus when

In load flow studies PV bus is treated as PQ bus when Correct Answer Reactive power goes beyond limit

Load Flow equations are non-linear and can be solved by an iterative method.

The iterative methods are

• Gauss’s method
• Gauss-Seidel method

Gauss-Seidel Iterative Method(Including PV Buses):

• In load bus P, Q are known quantities and in Voltage Controlled bus P is known and Q is not known.
• Therefore, for solving equation corresponding to voltage controlled bus Q must be calculated first.
• After Q at the voltage controlled bus has been calculated, it should be checked whether this value violates the reactive power generation at the bus.
• If the reactive power value violates, the voltage-controlled bus is made to act as load bus for that iteration only and the reactive power to be substituted in the expression for that iteration will correspond to the limit it has violated.