Abstract: This line-commutated converter, in one form, has a pair of D.C. terminals for connection to a D.C. system and a pair of A.C. terminals for connection to an A.C. system. The converter comprises first, second, third, and fourth branches, each comprising the combination of a thyristor and a diode connected in inverse-parallel and an inductor connected in series with this combination. The first and fourth branches with a first node located therebetween are connected in series across the D.C. terminals; and the second and third branches with a second node located therebetween are also connected in series across the D.C. terminals. The nodes are effectively connected across the A.C. terminals. Controlled gating means simultaneously triggers the first and second branches into conduction at a controlled phase angle with respect to the A.C. system voltage and simultaneously triggers the third and fourth branches into conduction 180 degrees thereafter, repeating this sequence each cycle of the A.C. system voltage.

Abstract: A regulating system for delivering a leading or lagging current to compensate for a load varying reactance is disclosed. The regulating system has an RMS composite controller for regulating the voltages at a critical area in a power system at which good voltage regulation is desired. In various embodiments the RMS composite controller has an arrangement to develop RMS quantities representative of the sequence components of the three phase power system. Each of the various RMS composite controllers provides an accurate control signal for the desired voltage regulation.

Abstract: In an alternating current electric power system of the type subject to rapid load voltage regulation as a result of variations in reactive load current, reactive load current compensation is provided by fixed capacitors and inductors in parallel with the load. The inductors are in series with static switches which are phase controlled to continuously maintain the net reactive compensating current substantially equal and opposite to the reactive components of load currents. Compensation control determines firing time of thyristor switches in accordance with the magnitude of reactive load current. In one embodiment, a signal representative of the condition of the reactive load current is provided with a positive phase shift correction to compensate for a negative phase shift which is provided by the thyristor switching technique.

Abstract: A dc measuring circuit for power rectifiers is described wherein primary line current is utilized to measure direct current output. In the measuring circuit, line current transformers are connected to a multiphase instrument rectifier through a phase shifting current transformer which is adjustable to compensate for differences between the primary and secondary line current phase shift characteristics of the power transformer and any phase shift in the line current transformer. By such compensation, the average value of rectified primary line current in the measuring circuit is maintained independent of the commutating angle of the rectified power current. The dc measuring circuit includes means for providing unity current transformation through the phase shifting current transformer. The dc measuring circuit also includes means for handling the presence of zero sequence current without causing measurement error or circuit damage.

Abstract: A voltage regulating system for an AC electrical power system includes a reactive converter having fixed capacitors and fixed inductors. Static switching devices are provided and include gating circuits for controlling the conduction angle of the switching devices so as to control the magnitude of the reactive current traversing the fixed inductors. RMS transducer circuitry is provided for generating an electrical signal representative of the RMS value of the voltage waveform at a critical point in the AC power system at which good voltage regulation is desired. Circuitry is provided for generating an electrical signal representative of a desired RMS value. Comparison components are provided for comparing these two electrical signals and generating an output signal for use in controlling the conduction angle of the switching devices so as to regulate the magnitude of the voltage waveform at the critical point in the AC power system.

Abstract: In an alternating current electric power system of the type subject to rapid load voltage regulation as a result of variations in reactive load current, reactive load current compensation is provided by fixed capacitors and inductors in parallel with the load, the inductors being in series with static switches which are phase controlled to continuously maintain the net reactive compensating current substantially equal and opposite to the reactive component of load current. Compensation control determines firing time of static switches in accordance with the magnitude of reactive load current. The compensation control includes means rapidly responsive to rapid current disturbances. In one embodiment, the compensation control includes devices for continuously sensing the phase and magnitude of the reactive load current. In another embodiment, the compensation control includes devices for sensing the phase and magnitude of the reactive load current 12 times per cycle of source frequency.

Abstract: A reactive current compensator for improving the power factor of a multiphase alternating current electric power circuit comprises a bank of fixed capacitors connected to multiphase line terminals in star circuit relation and two multiphase banks of fixed inductors connected to said terminals in parallel circuit relation, one inductor bank being star-connected and the other being ring connected, together with switching means responsive to a characteristic of power circuit current for controlling the magnitude of current in each phase of both inductor banks.

Abstract: In an alternating current electric power system subject to rapid load voltage regulation as a result of variations in reactive load current, reactive load current compensation is provided by fixed capacitors and inductors in parallel with the load, the inductors being in series with static switches which are phase controlled to continuously maintain the net reactive compensating current substantially equal and opposite to the reactive component of load current. Compensation control determines firing time of the static switches in accordance with the magnitude of reactive load current and regulating means additionally controls firing time to maintain line current and voltage at a selected line location substantially in phase coincidence.

Abstract: Reactive current compensating apparatus for a multiphase electric power circuit comprises separately variable reactive impedance elements coupled to the power circuit in multiphase relation through phase shifting means such as a tertiary transformer winding. When phase voltage supplied to the compensating impedance leads or lags the line-to-neutral voltage of the power circuit the compensating effect in respect to negative phase sequence line current components is enhanced as compared to direct conductive connection of compensating impedance to the power circuit.

Abstract: A semiconductor valve type converter for supplying single phase load current at power frequency from an N phase polyphase power system without unbalance of polyphase current or voltage comprises a transformer having KN secondary phase voltages displaced by 180/KN electrical degress (where K is an integer) and a bridge type thyristor network for connecting each secondary phase voltage source alternately to positive and negative network buses. The network buses are connected through a centertapped reactor with the single phase load connected between the reactor tap and the secondary phase voltage sources. A commutating circuit effectively connected across the last thyristor to fire during each positive and negative half cycle of single phase output voltage may be provided if necessary to effect the network reversal of single phase current at each half cycle of power frequency.

Abstract: A DC measuring circuit for power rectifiers is described wherein primary line current is utilized to measure direct current output. In the measuring circuit line current transformers are connected to a multiphase instrument rectifier through a phase shifting current transformer which is adjustable to compensate for difference between the primary to secondary line current phase shift characteristic of the power transformer and any phase shift in the line current transformers. By such compensation the average value of rectified primary line current in the measuring circuit is maintained independent of the commutating angle of the rectified power current.

Abstract: To control the gating angles and hence the subsequent conduction angles of a complementary pair of alternately fired controllable electric valves, there is provided during intermittent intervals when neither valve is conducting a gating control signal which depends on the sum of a control signal indicative of a desired conduction angle, an on-time indicating signal indicative of the actual conduction angle of the last conducting valve, and an off-time indicating signal that varies with the duration of the non-conducting interval. Each time the gating control signal reaches a predetermined threshold level, the next to conduct valve is fired.

Abstract: In an alternating current electric power system subject to rapid load voltage regulation as a result of variations in reactive load current, reactive load current compensation is provided by fixed capacitors and inductors in parallel with the load, the inductors being in series with static switches which are phase controlled to continuously maintain the net reactive compensating current substantially equal and opposite to the reactive component of load current. Compensation control determines firing time of the static switches in accordance with the magnitude of reactive load current and regulating means additionally controls firing time to maintain line current and voltage at a selected line location substantially in phase coincidence.