Steady-state simulation of h.v. d.c. convertors by digital computers

Abstract

The paper introduces and develops a digital-computer technique for the steady-state simulation of h.v. d.c. convertors incorporating capacitive networks, such as filter circuits, damping circuits etc. The method involves the simulation of a single process of 60° starting from a valve firing, and, assuming steady-state and symmetrical operation, the relating of the conditions at the end of the 60° process to those at the beginning of the process. Since the system of differential equations constitutes a boundary-value problem, a digital solution is achieved by a finite-difference method which offers a most economical approach in computing time. The possibility of solution by iterative methods is also discussed. In the test network, including filter circuits, the a.c. system is taken to be inductive, but the method presented in the paper is suitable for further extensions in the network included. The simulation offers a facility for obtaining current and voltage waveforms in various circuit elements without excessive computing time, and could be useful in the design of filter circuits and damping circuits, in the assessment of convertor regulation and in checking the validity of simplified networks for the solution of steady-state convertor problems.