An iterative and decoupled method is proposed for solving the general active/reactive constrained power flow problem, based on rectangular coordinates of injected currents. Successive linear programming with dual-relaxation method is used. The general objective function is designed to accommodate security improvement as well as economical optimization, including system active losses. A hierarchical approach for reactive optimization is proposed. A whole optimization problem is thus subdivided into several subproblems which can be optimized independently, starting from predetermined boundary conditions. The performance of the algorithms is evaluated on real systems.