Frequency-dependent A.C. system equivalents for harmonic studies and transient convertor simulation
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
This thesis describes the algorithms developed for synthesizing frequency matched a.c. system equivalents for use with a Transient Convertor Simulator program. Two synthesis methods are outlined, with the merits of each being illustrated by applying them to the lower South Island portion of New Zealand's primary transmission system. Validation of the diakoptical technique used to model the frequency dependent mutual coupling, as well as data preparation, is achieved by using the current source model to inject harmonic currents into the frequency-matched a.c. system equivalent. The need for frequency matched a.c. system equivalents is demonstrated by using the Transient Convertor Simulator program for harmonic penetration studies. Finally the effect of the frequency-dependence of an a.c. system model on the transient behaviour of a convertor is illustrated by simulating both a.c. and d.c. disturbances. The difference in transient behaviour with asymmetric a.c. faults as well as the harmonic assessment for harmonic penetration studies both demonstrate the need for frequency matched a.c. system equivalents that more accurately model the actual system.