A modified Levenberg-Marquardt approach to explore the limit operation state of AC/DC hybrid system

This paper is concerned with the limit operation state of AC/DC hybrid system based on the alternate iterative method to solve the AC/DC power flow. A modified Levenberg-Marquardt (LM) method is employed to solve the nonlinear equations of AC power flow and DC equations, respectively. Then, the heavy load system is constructed by expanding the same times of real and reactive load to explore the limit operation state. Simulation results show that modified LM method has good convergent property to solve the nonlinear equations, especially for the heavy load system. Also, when the expanding times of load exceeds the maximal times of load withstood by Newton method, there exists no solution obtained by Newton method, while the least square solutions obtained by LM method can provide useful information for Newton method to take some measurements on weak nodes to enlarge the scope of the limit operation state.