Control-system stability in multiterminal h.v. d.c. systems

A linearised analysis of a multiterminal h.v. d.c. system leads to a stability criterion in a convenient form for assessing the results of changes in controller properties at one terminal. Constant-current, constant-power and constant-extinction-angle control are considered in detail, and the stability of various control configurations is examined. The predictions of the small-signal analysis are verified by digital simulation for these cases and for changes in the smoothing-reactor size, the length of a branch of the d.c. line, and the controller transfer functions.