Newton- Raphson method: The Newton - Raphson method is the type of open method (Extrapolation method). It is a powerful technique for solving algebraic and transcendental equations f( x ) = 0, numerically. It is an iteration method for solving a set of various nonlinear equations with an equal number of unknowns. Advantages: It possesses quadratic convergence characteristics. Therefore, the convergence is very fast. The number of iterations is independent of the size of the system. The Newton-Raphson Method convergence is not sensitive to the choice of slack bus. Overall, there is a saving in computation time since a fewer number of iterations are required. Disadvantages: It does not converge to a root when the second differential coefficient changes sign It is sensitive to the starting value. Convergence fails if the starting point is not near the root. It is not preferred when the graph of f(x) is nearly horizontal where it crosses the x-axis as the values of f’(x) have negative values in this case.