Abstract: The novel circuit arrangement is used for the static generation of a variable electric output, as is common in static reactive-power compensation systems. According to the invention, a voltage is applied to a consumer, i.e. to a capacitor and/or an inductor, and a transformer (T) has at least two power-control windings (W1, W2) in a secondary circuit, said windings being connected electrically in series via bridge circuits (B1, B2). In their branches, the bridge circuits contain static switches (BSS1 . . . 4) in an inverse-parallel connection, said switches can be selectively connected or disconnected.

Abstract: The novel circuit arrangement is used for the static generation of a variable electric output, as is common in static reactive-power compensation systems. According to the invention, a voltage is applied to a consumer, i.e. to a capacitor and/or an inductor, and a transformer (T) has at least two power-control windings (W1, W2) in a secondary circuit, said windings being connected electrically in series via bridge circuits (B1, B2). In their branches, the bridge circuits contain static switches (BSS1 . . . 4) in an inverse-parallel connection, said switches can be selectively connected or disconnected.

Abstract: The invention is for an ac-dc converter with an integrated SVC, which would provide independent control of the active and reactive power. In a three-phase bridge converter, the SVC is either connected to on the valve side of converter transformer or to the converter transformer itself. In the latter case, the SVC could be connected to a tertiary winding of the converter transformer, or one common transformer could function as the converter transformer and the SVC transformer. Any type of SVC, including the recently developed Voltage Controlled SVC could be used as the SVC for the three-phase bridge converter with integrated SVC. The ac-dc converter with integrated SVC could eliminate the need for on-load tap changers for the converter transformer. It could also reduce the size and losses in converter transformers. The SVC could also be modified to include harmonic filters for filtering harmonics from ac-dc conversion to get added savings in transformer size and losses.

Abstract: An ac-dc converter using bi-directional thyristor valves made up of back-to-back connected thyristors as converter valves. The bi-directional thyristor valves permit operation of the converter as a rectifier or an inverter with both polarities of the voltage across the dc terminals of the converter. The bi-directional valves can be used to prevent the reversal of the polarity of the dc voltage across the dc terminals of the converter or to minimize the magnitude of the reverse voltage. The bi-directional thyristor valves can be used to provide protection against overvoltage across the converter valves and eliminate or reduce the energy rating of converter valve arresters.

Abstract: A switching scheme that permits a thee phase capacitor bank to have two ratings depending on whether the circuit is connected in delta or star configuration The capacitor per phase consists of two sections. In delta connection the two sections are connected in series. In the star connection the two sections are connected in parallel. Both the changes —the delta connection to the star connection of the circuit and the series connection of the capacitor sections to the parallel connection of the capacitor sections—are accomplished simultaneously by a single switching operation of three star connected switches. In the case of isolated neutral, the number of switches can be reduced from three to two.

Abstract: An AC generator whose field winding (4) on the rotor is excited by AC so that the resultant speed of the rotating field is the algebraic sum of the rotor speed and the speed of the field relative to the rotor itself. This makes it possible to generate AC at a frequency different from that of conventional DC excited generators by the appropriate choice of the frequency of the AC input to the rotor field circuit. It enables the stabilization of the output frequency of the alternator when speed changes occur, by the adjustment of the AC frequency of the rotor input. The AC fed to the rotor is from an auxiliary winding (3) which may be housed on the rotor itself, thereby eliminating the need for any brushes or slip rings. The AC is induced in the auxiliary rotor winding by having an auxiliary winding on the stator (2), distinct from the main stator winding (1). The input to the stator auxiliary winding may be from an inverter (5) whose frequency may be adjustable.

Abstract: An HVDC transmission has two converters (SR1, SR2). Each converter is connected between an alternating-voltage network (N1, N2) and a d.c. link (L1, L2) common to the converters. At least one converter is connected to its alternating-voltage network without the use of any full transformer, for example directly, or via an inductor or an autotransformer, or via series capacitors. The transmission has a mutual inductor (IB) which is arranged on the d.c. side of the converter and which has two windings (IB1, IB2) which are each connected to a respective one of the d.c. supply lines of the converter and are magnetically coupled to each other, the inductor being designed and connected so as to exhibit a high impedance to ground mode currents.

Abstract: A static controlled reactance device is inserted in series with an AC electric power transmission line to adjust its transfer impedance. An inductor (reactor) is serially connected with two back-to-back connected thyristors which control the conduction period and hence the effective reactance of the inductor. Additional reactive elements are provided in parallel with the thyristor controlled reactor to filter harmonics and to obtain required range of variable reactance. Alternatively, the static controlled reactance device discussed above may be connected to the secondary winding of a series transformer having its primary winding connected in series to the transmission line. In a three phase transmission system, the controlled reactance device may be connected in delta configuration on the secondary side of the series transformer to eliminate triplen harmonics.