POWER-FLOW ANALYSIS IN MTDC-AC SYSTEMS - A NEW APPROACH

This paper presents a new approach to the power flow analysis in stead y state for multiterminal DC-AC systems. A flexible and practical choi ce of per unit system is used to formulate the DC network and converte r equations. A converter is represented by Norton's equivalent of a cu rrent source in parallel with the commutation resistance. Unlike in pr evious literature, the DC network equations are used to derive the con troller equations for the DC system using a subset of specifications. The specifications considered are current or power at all terminals ex cept the slack terminal where the DC voltage is specified. The control equations are solved by Newton's method, using the current injections at the converter terminals as state variables. Further, a systematic approach to the handling of constraints is proposed by identifying the priorities in rescheduling of the specified variables. The methodolog y is illustrated by example of a 5 terminal DC system.