Solution of ac/dc power flow on a multiterminal HVDC system: Illustrative case supergrid phase I

This paper presents an algorithm for the sequential solution of the ac/dc power flow, which is proposed for the analysis of multi-terminal HVDC systems (MTDC). This sequential power flow algorithm can be implemented easily in an existing ac power flow package and is very flexible when it compared with unified methods. Gauss-Siedel algorithm is used to solve dc power balance equations, it offers two keys advantages: very fast and simple computational implementation, and errors do not accumulate during the calculation. The algorithm is tested using the WSCC 3-machine, 9-bus system with a 3-terminal MTDC network and results compared with those obtained from DIgSILENT^® PowerFactory^TM demonstrating the validity of the proposed algorithm. As aggregate value, a representative test case of the projected scheme for the phase I of the Supergrid project on the North Sea is presented, the proposed approach presented in this paper is used to calculate DC power flows for some scenarios.