Question

In a 100 bus power system, there are 10 generators. In a particular iteration of Newton Raphson load flow technique (in polar coordinates), two of the PV buses are converted to PQ type. In this iteration,

• A. the number of unknown voltage angles increases by two and the number of unknown voltage magnitudes increases by two.
• B. the number of unknown voltage angles remains unchanged and the number of unknown voltage magnitudes increases by two
• C. the number of unknown voltage angles increases by two and the number of unknown voltage magnitudes decreases by two
• D. the number of unknown voltage angles remains unchanged and the number of unknown voltage magnitudes decreases by two

Answer 1

The correct option is B the number of unknown voltage angles remains unchanged and the number of unknown voltage magnitudes increases by two

The voltage angles are the common variable for both PV and PQ buses, so it remains unchanged. Where as voltage magnitude is specified in PV bus and not specified in PQ bus, so it increases by two.