The Inclusion of HVDC Control Modes in a Three-Phase Newton-Raphson Power Flow Algorithm

A three-phase Newton-Raphson power flow algorithm with conventional HVDC power plant modelling is presented in this paper. Emphasis is placed on the representation of converter control modes. The solution approach takes advantage of the strong numerical convergence afforded by the Newton-Raphson method in polar coordinates to yield reliable numerical solutions for combined HVAC-HVDC systems, where power plant and operational imbalances are explicitly taken into account. Although well-developed algorithms exist for solving fundamental frequency, three-phase power flows or combined power flows/harmonic currents, no HVDC converter control mode representation appears to have been addressed in the numerically reliable three-phase Newton-Raphson method. Two test cases are solved, one corresponding to a small system to enable reproduction of results by interested readers and the other is a large system containing several HVDC links and operational control modes.