Controllable phase shifter

Abstract

Controllable phase shifters containing reactances and valve switching devices are used for compensation and stabilizing purposes in alternating current-energy transmission systems. There is desired a phase shift which can be continuously controlled within variable limits and with comparatively low expenditure in circuit components. There is provided at least one shunt circuit branch between primary terminals having mutual phase shifted voltages, and a tap provided as a secondary terminal supplies a secondary voltage or potential having a phase between that of the primary terminals. At both sides of the secondary terminal there are arranged in the shunt circuit branch preferably complementary reactive impedances. At least one valve switching device, controllable with respect to its gating behavior, is arranged in series or parallel to one such impedance and renders possible changing the magnitude of the impedance which is effective for the fundamental oscillation, and thus, a change of the control phase angle. Preferably valve switching devices are provided at both sides, and, if desired, in combination parallel and in series with the impedances to both sides of the secondary terminal, thereby realizing the advantage of a phase angle control in both directions and over wide ranges of the primary phase angle.