Dynamic simulation of h.v.d.c. transmission systems on digital computers

The paper introduces and develops a new digital-computer technique for the dynamic study of an h.v.d.c. system. The authors have called this technique the `central-process¿ method, and it is based on the fact that the operation of an h.v.d.c. convertor consists of similar consecutive processes, each process having features which are common to all processes. In this method, each bridge convertor of an h.v.d.c. system is represented by a central process, and repetitive use of the latter simulates continuous convertor operation. These central processes are mathematically represented by a set of differential and Boolean equations. Any h.v.d.c. system may be represented by mathematical connection of central processes simulating the connection of bridges in a true system. This technique may be employed to obtain the waveforms of transient or steady-state voltages and currents anywhere in the d.c. system. To illustrate this method, an h.v.d.c. link is considered; the link which connects two independent a.c. systems comprises two convertors with their control systems, and a d.c. transmission line. As an example, the transient behaviour of the system is examined, following changes in the current settings of the control system.