The necessary equation to be solved during the load flow analysis using Fast-Decoupled methid is given below:where B' and B'' are formed using the imaginary part of the bus admittance matrix Ybus, n is the total number of buses in the system, m is the number of voltage regulated buses. The size of matrix B' is∆P/|Vi|= -B' ∆δ∆Q/|Vi| = -B'' ∆|Vi|

• A. (m-1) x (m-1)
• B. (n-1) x (n-1)
• C. (n-m) x (n-m)
• D. (n-m-1) x (n-m-1)

Answer: (B)

In FDLF method,
B' corresponds to susceptance of unknown of PQ and PV bus
Order of B' matrix is = (n -1)*(n - 1)
Where n is total no. of buses.
Order of B'' = (n - m - 1)*(n - m - 1)