Fast Decoupled¶
The fast decoupled method is a fantastic power flow algorithm developed by Stott and Alsac [FD]. The method builds on a series of very clever simplifications and the decoupling of the Jacobian matrix of the canonical NewtonRaphson algorithm to yield the fastdecoupled method.
The method consists in the building of two admittancebased matrices and which are independently factorized (using the LU method or any other) which then serve to find the increments of angle and voltage magnitude separately until convergence.
Finding and ¶
To find we perform the following operations:
To find we perform the following operations:
The fastdecoupled algorithm¶
Factorize
Factorize
Compute the voltage module
Compute the voltage angle
Compute the error
Check the convergence
Iterate; While convergence is false and the number of iterations is less than the maximum:
Solve voltage angles (Piteration)
Update voltage
Compute the error (follow the previous steps)
Check the convergence (follow the previous steps)
If the convergence is still false:
Solve voltage modules (Qiteration)
Update voltage
Compute the error (follow the previous steps)
Check the convergence (follow the previous steps)
Increase the iteration counter.
End
[FD] 
