Abstract
M.Ing. (Electrical Engineering)
This thesis primarily addresses the subject of analysis and compensation of fictitious
power instantaneously: Fictitious power is defined as that component of apparent
power which does not contribute to the nett transfer of energy from source to load.
The dynamic characteristics of contemporary electric loads are of such orders of
magnitude that the load current contains severe changes 'within a fundamental frequency
cycle. Furthermore, such changes might not be periodic but may only
appear for short durations. Likewise, load current unbalance may also reach
intolerable levels, only for relatively short durations of time. Power theories based
on the classic active current approach has the characteristic that calculated magnitudes
are only available after some time has elapsed, which usually is a fundamental
frequency period. The original instantaneous power theory calculates active and fictitious
current magnitudes instantaneously, but these obtained values do not relate
to the classic values. Classic static VAr compensator dynamic operation limits lie
at switching twice per fundamental frequency cycle, with the result that intra-eycle
changes in the load current cannot be compensated. Distortion compensators' comprise
an energy storage element and a high frequency converter with dynamic
characteristics to compensate instantaneously for fictitious power components.
The revised instantaneous power theory is proposed in this thesis and is a combination
of the classic active current theory and the original instantaneous power
theory. The revised instantaneous power theory generates the fictitious currents
instantanenously. A distortion compensator is combined in parallel with the classic
static VAr compensator to obtain the hybrid fictitious power compensator. This
compensator has dynamic characteristics to match the revised instantaneous power
theory and to compensate for high dynamic load current variations within one fundamental
cycle. The revised instantaneous power theory is implemented as primary
control of a hybrid fictitious power compensator. The error modulation automatic
control technique for the distortion compensator is proposed and implemented with
improved results in distortion current compensation and current-fed distortion
compensator stability. The secondary control of the hybrid fictitious power
compensator concerns the feedback of the generated hybrid fictitious power
compensator currents. The control of the hybrid fictitious power compensator is
done with a personal computer in parallel with analog circuitry. The computer has
an on-board dedicated data acquisition and output card. The hybrid fictitious
power compensator is demonstrated on two experimental loads and the revised
instantaneous power theory is demonstrated on three experimental loads.