Energy extraction system from a capacitive source with shunt switching

Abstract

A system for and a method of extracting energy from a capacitive source, for example the energy induced in an insulated section of the overhead wire of an AC transmission line. The energy is extracted from the overhead wire by tapping the primary winding of a voltage step-down transformer which develops at its secondary an AC voltage the value of which is regulated through shunt switching. The shunt switching regulation as such is achieved by power thyristors the firing of which is selectively controlled in accordance with the phase and the amplitude of the output voltage. A comparator is used to compare the output voltage value with that of a signal delivered by an internal ramp generator. Moreover, the firing instant of the thyristors is governed by the output signal of the comparator and also in function of the information on the polarity of the output voltage cycles. Such shunt switching regulation allows the extraction from the overhead wire a maximum of power per kilometer of insulated wire and ensures a high stability of the output voltage despite substantial variations in the load connected to the secondary of the step-down transformer. The instant extracting system allows inter alia an economic and steady supply of power to microwave repeater stations which usually run along energy transmission lines and remote from central supply sources.