Newton Raphson method is used to solve

SOLUTION

• Load flow study determines the operating state of the system for a given loading.
• Load flow solves a set of simultaneous non-linear algebraic power equations for the two unknown variables (|V| and ∠δ) at each node in a system.
• The output of the load flow analysis is the voltage and phase angle, real and reactive power (both sides in each line), line losses, and slack bus power.
• Gauss seidel, Newton Raphson, and Fast decoupled load flow method are the different load flow methods.
• The fast decoupled load flow method gives an approximate load flow solution because it uses several assumptions. Accuracy depends on the power mismatch vector tolerance.

• The fast decoupled load flow method is an extension of the Newton-Raphson method formulated in polar coordinates with certain approximations, which results in a fast algorithm for load flow solution.

• The fast decoupled method requires a greater number of iterations than the Newton-Raphson method.

​Important Points:

Gauss-Seidel Method	Newton Raphson Method
Load flow equations are non-linear algebraic in rectangular coordinates	Load flow equations are non-linear algebraic in polar co-ordinates
It has linear convergence characteristics	It has quadratic convergence characteristics
Less memory requirement	More memory requirement
Computation time per iteration is less	Computation time per iteration is more
Require a large number of iterations to reach convergence	Require a smaller number of iterations to reach convergence
Total time is taken to get convergence is high	Total time taken to get convergence is less
The number of iterations required to get for convergence increases with the size of the system i.e. the number of buses	The number of iterations is independent of the size of the system
As the selection of slack bus is changed, the convergent criteria also will change	The convergent criteria is independent of the selection of slack bus
Unreliable convergent, less accurate and used for smaller system	Reliable convergent, more accurate, it can be used for larger power system