Constrained load flow model with two-terminal HVDC

This paper proposed a constrained load flow(CLF) model of AC/HVDC power systems. In this load flow model, the generation output and the control parameters of two-terminal HVDC systems can be limited within their bilateral constraints rather than specified as in the conventional model. The proposed model can ensure the rationality of the results while enlarging the convergence region of the power flow. It is transformed to a nonlinear programming problem and solved by trust-region Gauss-Newton method, which is suitable for underdetermined problems, so that we multiple slack generators can be set flexibly. Trust-region Gauss-Newton method is globally convergent, so in a solvable power flow, a feasible solution can be obtained. In an unsolvable case, a solution for system adjustment can be obtained by entirely slacking certain control variables. The effectiveness and flexibility of the proposed model is proved by simulation results on a general test system.