In the field of monitoring assemblies for gas tube switching devices which is operable in a plurality of different conducting modes, a monitoring assembly includes a monitoring module to distinguish in real time at least one conducting mode from the or each other conducting mode.

In the field of monitoring assemblies for gas tube switching devices which is operable in a plurality of different conducting modes, a monitoring assembly includes a monitoring module to distinguish in real time at least one conducting mode from the or each other conducting mode.

A high-voltage direct-current (HVDC) transmission system includes an alternating current (AC) electrical source and a power converter channel that includes an AC-DC converter electrically coupled to the electrical source and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and the DC-AC inverter each include a plurality of legs that includes at least one switching device. The power converter channel further includes a commutating circuit communicatively coupled to one or more switching devices. The commutating circuit is configured to switch on one of the switching devices during a first portion of a cycle of the H-bridge switching circuits and switch off the switching device during a second portion of the cycle of the first and second H-bridge switching circuits.

A high-voltage direct-current (HVDC) transmission system includes an alternating current (AC) electrical source and a power converter channel that includes an AC-DC converter electrically coupled to the electrical source and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and the DC-AC inverter each include a plurality of legs that includes at least one switching device. The power converter channel further includes a commutating circuit communicatively coupled to one or more switching devices. The commutating circuit is configured to switch on one of the switching devices during a first portion of a cycle of the H-bridge switching circuits and switch off the switching device during a second portion of the cycle of the first and second H-bridge switching circuits.

Methods and power conversion systems in which a capacitor degradation detection system includes an adjustable gain amplifier circuit is calibrated by automatic adjustment of at least one amplifier gain to accommodate current and voltage levels of a particular filter circuit in a first mode. Capacitance values of filter capacitors are calculated according to amplified current signals and compared with an acceptable tolerance range to selectively identify a filter capacitor fault or to store calculated capacitance values as base values in an electronic memory in the first mode. During operation in a second mode with the rectifier and inverter on, the adjusted amplifier gain is used to amplify current sensor signals and/or voltage signals, and capacitance values of the filter capacitors are used to selectively identify capacitor degradation.

A high-voltage direct-current (HVDC) transmission system includes an alternating current (AC) electrical source and a power converter channel that includes an AC-DC converter electrically coupled to the electrical source and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and the DC-AC inverter each include a plurality of legs that includes at least one switching device. The power converter channel further includes a commutating circuit communicatively coupled to one or more switching devices. The commutating circuit is configured to switch on one of the switching devices during a first portion of a cycle of the H-bridge switching circuits and switch off the switching device during a second portion of the cycle of the first and second H-bridge switching circuits.