Integrated AC/DC systems power flow solution using Newton-Raphson and Broyden approaches

A new modified system of equations for solving AC/DC power flow is proposed in this paper using two different methods. The well-known Jacobian equation for the AC power flow is modified to achieve compatibility for systems with integrated DC link(s) in the AC network. The converters are treated as voltage dependent PQ-buses. This allows the DC variables to be included in the power flow equations. The new residual vector and Jacobian matrix comprise both the AC network and the DC link. A secant method called Broyden´s method is applied for solving the nonlinear systems of equations. This solution is compared to that of Newton-Raphson´s method. The IEEE 9-bus test system is used to validate these methods.