Abstract: In the high voltage d-c transmission (HGU) power station in a block circuit, a three-phase generator feeds a 12-pulse high voltage d-c transmission (HGU) short coupler through at least one shifting transformer which serves for forming voltages of two three-phase voltage systems phase-shifted relative to each other by 30.degree. el. As compared to a full transformer, the shifting transformer can be constructed for substantially less power, which reduces the cost and the losses of the station. While the voltages of the two phase-shifted voltage systems can be taken off at the external terminals of the secondary windings of the shifting transformer, the center taps of the secondary windings are acted upon by the generator voltage. Advantageously, the high voltage d-c transmission short coupler is formed of a multiplicity of parallel, electrically separate d-c circuits which can be fed by separate shifting transformers.

Abstract: In order to place into operation a group of power converters which are connected in series as concerns the direct-current mode and in parallel as concerns the alternating-current mode, of a power or current converter operating in a rectifying mode of a high-voltage direct-current transmission installation, the control pulses of the group of power converters to be placed into operation are set at a range of approximately 100 to 115 electrical degrees. The bypass or shunt switch of such group of power converters subsequently receives an opening command. The control pulses, after accomplishment of opening of the bypass or shunt switch are shifted in accordance with a predetermined linear ramp function in the rectifying range and thereafter the control pulses are delivered by means of a pole current regulator. The placement into operation of a power converter operating in the inverting mode is accomplished in a similar fashion.

Abstract: A method and apparatus for controlling the real and reactive power behavior of a high voltage transmission (HDT) system characterized by a rectifier station connected to a first three phase network and an inverter station connected to a second three phase network. The rectifier and inverter stations have positive and negative station-halves connected to each other over positive and negative D.C. transmission lines to form positive and negative poles, each station having a common ground or return wire. Each station is equipped with current and voltage regulators, as well as control angle and quenching angle regulators whereby in case of the tripping of line protective devices monitoring line current in a faulty pole, and the consequent unloading of the faulty pole, the regulation of the intact pole assumes control for a short time to protect against network transients resulting from the load drop.

Abstract: A double-pole high-voltage direct-current transmission system is provided with two stations and an overhead line or cable, each of the stations having rectifier bridges connected in series from a positive line pole to a ground electrode and from the ground electrode to a negative line pole. The ground or earth serves as return line if one of the line poles should fail. The ground electrode at one of the stations is a depth electrode regularly operated as an anode, and the ground electrode at the other of the stations is regularly operated as a cathode. Two pairs of reversing switches are provided, each of the pairs, when the other of the stations is operated as a rectifier, being connected on the direct-current side of and to the respective rectifier bridges located between the negatively operated line pole and the depth electrode, on the one hand, and between the negatively operated line pole and the ground electrode operated as a cathode, on the other hand.

Abstract: A method and apparatus for regulation of the power factor of a 3-phase network fed with power from another 3-phase network via a short high-voltage direct current transmission link interconnecting the two networks. The d.c. transmission link includes rectifier and inverter stations connected at opposite ends of the link and the inverter station is controlled in such manner as to supply power to the fed network at a variable leading power factor in dependence upon the actual power factor of the fed network.

Abstract: A transmission substation for transforming a high D.C. voltage over an intermediate three phase A.C. network into a lower D.C. voltage. The substation includes an arrangement of inverters and rectifiers for effecting the transformation with reduced losses. Also encompassed is a similar reversed arrangement for stepping up from a lower D.C. voltage to a higher D.C. voltage.